I know this error is specific to this particular sketch, but please bear with me; when I try to compile this against an Arduino Nano/Uno (with Arduino IDE 1.8.15) the compiler complains that 'MonoOutput' has not been declared, like so:

Triple_DCO_1.3:697:14: error: 'MonoOutput' has not been declared return MonoOutput::from8Bit((aSin1.next() * (pgm_read_byte(&(gain_table[0][gain]))) / 512 + aSin2.next() * (pgm_read_byte(&(gain_table[1][gain]))) / 512 + aSin3.next() * (pgm_read_byte(&(gain_table[2][gain]))) / 512 + aSin4.next() * (pgm_read_byte(&(gain_table[3][gain]))) / 512 + aSin5.next() * (pgm_read_byte(&(gain_table[4][gain]))) / 512 + aSin6.next() * (pgm_read_byte(&(gain_table[5][gain]))) / 512 + aSin7.next() * (pgm_read_byte(&(gain_table[6][gain]))) / 512 )*Gain_CV_2/128); ^~~~~~~~~~

I have found that this issue has come up once on ModWiggler, once in YouTube comments, and once in the Mozzi GitHub repository (but in the last case only pertaining to the Nano Every and not a vanilla Nano), so I know it's not unique to my situation; but since most people don't seem to be experiencing this problem, it must be something particular to my setup or am missing something obvious.

The code in question (Triple_DCO_1.3.ino) is from luislutz GitHub; it is too long to post here, but a simpler version of the sketch, pasted below, exhibits exactly the same error for me:

#include <MozziGuts.h>
#include <Oscil.h> // oscillator template

#include <tables/saw2048_int8.h> // saw table for oscillator
#include <tables/square_no_alias512_int8.h> // saw table for oscillator
#include <tables/triangle_hermes_2048_int8.h> // saw table for oscillator
#include <tables/sin2048_int8.h> // sine table for oscillator
#include <tables/waveshape_chebyshev_3rd_256_int8.h> // sine table for oscillator
#include <tables/halfsin256_uint8.h> // sine table for oscillator
#include <tables/waveshape_sigmoid_int8.h> // sine table for oscillator
#include <tables/phasor256_int8.h> // sine table for oscillator

Oscil <SAW2048_NUM_CELLS, AUDIO_RATE> aSaw1(SAW2048_DATA);
Oscil <SAW2048_NUM_CELLS, AUDIO_RATE> aSaw2(SAW2048_DATA);
Oscil <SAW2048_NUM_CELLS, AUDIO_RATE> aSaw3(SAW2048_DATA);
Oscil <SAW2048_NUM_CELLS, AUDIO_RATE> aSaw4(SAW2048_DATA);
Oscil <SAW2048_NUM_CELLS, AUDIO_RATE> aSaw5(SAW2048_DATA);

Oscil <SQUARE_NO_ALIAS512_NUM_CELLS, AUDIO_RATE> aSqu1(SQUARE_NO_ALIAS512_DATA);
Oscil <SQUARE_NO_ALIAS512_NUM_CELLS, AUDIO_RATE> aSqu2(SQUARE_NO_ALIAS512_DATA);
Oscil <SQUARE_NO_ALIAS512_NUM_CELLS, AUDIO_RATE> aSqu3(SQUARE_NO_ALIAS512_DATA);
Oscil <SQUARE_NO_ALIAS512_NUM_CELLS, AUDIO_RATE> aSqu4(SQUARE_NO_ALIAS512_DATA);
Oscil <SQUARE_NO_ALIAS512_NUM_CELLS, AUDIO_RATE> aSqu5(SQUARE_NO_ALIAS512_DATA);

Oscil <TRIANGLE_HERMES_2048_NUM_CELLS, AUDIO_RATE> aTri1(TRIANGLE_HERMES_2048_DATA);
Oscil <TRIANGLE_HERMES_2048_NUM_CELLS, AUDIO_RATE> aTri2(TRIANGLE_HERMES_2048_DATA);
Oscil <TRIANGLE_HERMES_2048_NUM_CELLS, AUDIO_RATE> aTri3(TRIANGLE_HERMES_2048_DATA);
Oscil <TRIANGLE_HERMES_2048_NUM_CELLS, AUDIO_RATE> aTri4(TRIANGLE_HERMES_2048_DATA);
Oscil <TRIANGLE_HERMES_2048_NUM_CELLS, AUDIO_RATE> aTri5(TRIANGLE_HERMES_2048_DATA);

Oscil <SIN2048_NUM_CELLS, AUDIO_RATE> aSin1(SIN2048_DATA);
Oscil <SIN2048_NUM_CELLS, AUDIO_RATE> aSin2(SIN2048_DATA);
Oscil <SIN2048_NUM_CELLS, AUDIO_RATE> aSin3(SIN2048_DATA);
Oscil <SIN2048_NUM_CELLS, AUDIO_RATE> aSin4(SIN2048_DATA);
Oscil <SIN2048_NUM_CELLS, AUDIO_RATE> aSin5(SIN2048_DATA);

Oscil <CHEBYSHEV_3RD_256_NUM_CELLS, AUDIO_RATE> aChb1(CHEBYSHEV_3RD_256_DATA);
Oscil <CHEBYSHEV_3RD_256_NUM_CELLS, AUDIO_RATE> aChb2(CHEBYSHEV_3RD_256_DATA);
Oscil <CHEBYSHEV_3RD_256_NUM_CELLS, AUDIO_RATE> aChb3(CHEBYSHEV_3RD_256_DATA);
Oscil <CHEBYSHEV_3RD_256_NUM_CELLS, AUDIO_RATE> aChb4(CHEBYSHEV_3RD_256_DATA);
Oscil <CHEBYSHEV_3RD_256_NUM_CELLS, AUDIO_RATE> aChb5(CHEBYSHEV_3RD_256_DATA);

Oscil <HALFSIN256_NUM_CELLS, AUDIO_RATE> ahSin1(HALFSIN256_DATA);
Oscil <HALFSIN256_NUM_CELLS, AUDIO_RATE> ahSin2(HALFSIN256_DATA);
Oscil <HALFSIN256_NUM_CELLS, AUDIO_RATE> ahSin3(HALFSIN256_DATA);
Oscil <HALFSIN256_NUM_CELLS, AUDIO_RATE> ahSin4(HALFSIN256_DATA);
Oscil <HALFSIN256_NUM_CELLS, AUDIO_RATE> ahSin5(HALFSIN256_DATA);

Oscil <WAVESHAPE_SIGMOID_NUM_CELLS, AUDIO_RATE> aSig1(WAVESHAPE_SIGMOID_DATA);
Oscil <WAVESHAPE_SIGMOID_NUM_CELLS, AUDIO_RATE> aSig2(WAVESHAPE_SIGMOID_DATA);
Oscil <WAVESHAPE_SIGMOID_NUM_CELLS, AUDIO_RATE> aSig3(WAVESHAPE_SIGMOID_DATA);
Oscil <WAVESHAPE_SIGMOID_NUM_CELLS, AUDIO_RATE> aSig4(WAVESHAPE_SIGMOID_DATA);
Oscil <WAVESHAPE_SIGMOID_NUM_CELLS, AUDIO_RATE> aSig5(WAVESHAPE_SIGMOID_DATA);

Oscil <PHASOR256_NUM_CELLS, AUDIO_RATE> aPha1(PHASOR256_DATA);
Oscil <PHASOR256_NUM_CELLS, AUDIO_RATE> aPha2(PHASOR256_DATA);
Oscil <PHASOR256_NUM_CELLS, AUDIO_RATE> aPha3(PHASOR256_DATA);
Oscil <PHASOR256_NUM_CELLS, AUDIO_RATE> aPha4(PHASOR256_DATA);
Oscil <PHASOR256_NUM_CELLS, AUDIO_RATE> aPha5(PHASOR256_DATA);
#define CONTROL_RATE 128 // Hz, powers of 2 are most reliable

int freq1 = 110;//base freq
int voct = 1000;//external V/OCT LSB

int freqv1 = 440;//apply voct
int freqv2 = 440;
int freqv3 = 440;
int freqv4 = 440;
int freqv5 = 440;

byte note1 = 0;//Root
byte note2 = 0;//2nd
byte note3 = 0;//3rd
byte note4 = 0;//4th
byte note5 = 0;//Root

byte inv_aply1 = 0; //0 = no inv , 1 = inv , Root
byte inv_aply2 = 0; //2nd
byte inv_aply3 = 0; //3rd
byte inv_aply4 = 0; //4th
bool inv_aply5 = 0; //0 = no output root sound , 1 = output root sound

int inv = 0;
int inv_knob = 0;
int chord = 0;
byte wave = 0;//0=saw,1=squ,2=tri,3=sin,etc...

const static float voctpow[1024] PROGMEM = {
 0,  0.004882, 0.009765, 0.014648, 0.019531, 0.024414, 0.029296, 0.034179, 0.039062, 0.043945, 0.048828, 0.05371,  0.058593, 0.063476, 0.068359, 0.073242, 0.078125, 0.083007, 0.08789,  0.092773, 0.097656, 0.102539, 0.107421, 0.112304, 0.117187, 0.12207,  0.126953, 0.131835, 0.136718, 0.141601, 0.146484, 0.151367, 0.15625,  0.161132, 0.166015, 0.170898, 0.175781, 0.180664, 0.185546, 0.190429, 0.195312, 0.200195, 0.205078, 0.20996,  0.214843, 0.219726, 0.224609, 0.229492, 0.234375, 0.239257, 0.24414,  0.249023, 0.253906, 0.258789, 0.263671, 0.268554, 0.273437, 0.27832,  0.283203, 0.288085, 0.292968, 0.297851, 0.302734, 0.307617, 0.3125, 0.317382, 0.322265, 0.327148, 0.332031, 0.336914, 0.341796, 0.346679, 0.351562, 0.356445, 0.361328, 0.36621,  0.371093, 0.375976, 0.380859, 0.385742, 0.390625, 0.395507, 0.40039,  0.405273, 0.410156, 0.415039, 0.419921, 0.424804, 0.429687, 0.43457,  0.439453, 0.444335, 0.449218, 0.454101, 0.458984, 0.463867, 0.46875,  0.473632, 0.478515, 0.483398, 0.488281, 0.493164, 0.498046, 0.502929, 0.507812, 0.512695, 0.517578, 0.52246,  0.527343, 0.532226, 0.537109, 0.541992, 0.546875, 0.551757, 0.55664,  0.561523, 0.566406, 0.571289, 0.576171, 0.581054, 0.585937, 0.59082,  0.595703, 0.600585, 0.605468, 0.610351, 0.615234, 0.620117, 0.625,  0.629882, 0.634765, 0.639648, 0.644531, 0.649414, 0.654296, 0.659179, 0.664062, 0.668945, 0.673828, 0.67871,  0.683593, 0.688476, 0.693359, 0.698242, 0.703125, 0.708007, 0.71289,  0.717773, 0.722656, 0.727539, 0.732421, 0.737304, 0.742187, 0.74707,  0.751953, 0.756835, 0.761718, 0.766601, 0.771484, 0.776367, 0.78125,  0.786132, 0.791015, 0.795898, 0.800781, 0.805664, 0.810546, 0.815429, 0.820312, 0.825195, 0.830078, 0.83496,  0.839843, 0.844726, 0.849609, 0.854492, 0.859375, 0.864257, 0.86914,  0.874023, 0.878906, 0.883789, 0.888671, 0.893554, 0.898437, 0.90332,  0.908203, 0.913085, 0.917968, 0.922851, 0.927734, 0.932617, 0.9375, 0.942382, 0.947265, 0.952148, 0.957031, 0.961914, 0.966796, 0.971679, 0.976562, 0.981445, 0.986328, 0.99121,  0.996093, 1.000976, 1.005859, 1.010742, 1.015625, 1.020507, 1.02539,  1.030273, 1.035156, 1.040039, 1.044921, 1.049804, 1.054687, 1.05957,  1.064453, 1.069335, 1.074218, 1.079101, 1.083984, 1.088867, 1.09375,  1.098632, 1.103515, 1.108398, 1.113281, 1.118164, 1.123046, 1.127929, 1.132812, 1.137695, 1.142578, 1.14746,  1.152343, 1.157226, 1.162109, 1.166992, 1.171875, 1.176757, 1.18164,  1.186523, 1.191406, 1.196289, 1.201171, 1.206054, 1.210937, 1.21582,  1.220703, 1.225585, 1.230468, 1.235351, 1.240234, 1.245117, 1.25, 1.254882, 1.259765, 1.264648, 1.269531, 1.274414, 1.279296, 1.284179, 1.289062, 1.293945, 1.298828, 1.30371,  1.308593, 1.313476, 1.318359, 1.323242, 1.328125, 1.333007, 1.33789,  1.342773, 1.347656, 1.352539, 1.357421, 1.362304, 1.367187, 1.37207,  1.376953, 1.381835, 1.386718, 1.391601, 1.396484, 1.401367, 1.40625,  1.411132, 1.416015, 1.420898, 1.425781, 1.430664, 1.435546, 1.440429, 1.445312, 1.450195, 1.455078, 1.45996,  1.464843, 1.469726, 1.474609, 1.479492, 1.484375, 1.489257, 1.49414,  1.499023, 1.503906, 1.508789, 1.513671, 1.518554, 1.523437, 1.52832,  1.533203, 1.538085, 1.542968, 1.547851, 1.552734, 1.557617, 1.5625, 1.567382, 1.572265, 1.577148, 1.582031, 1.586914, 1.591796, 1.596679, 1.601562, 1.606445, 1.611328, 1.61621,  1.621093, 1.625976, 1.630859, 1.635742, 1.640625, 1.645507, 1.65039,  1.655273, 1.660156, 1.665039, 1.669921, 1.674804, 1.679687, 1.68457,  1.689453, 1.694335, 1.699218, 1.704101, 1.708984, 1.713867, 1.71875,  1.723632, 1.728515, 1.733398, 1.738281, 1.743164, 1.748046, 1.752929, 1.757812, 1.762695, 1.767578, 1.77246,  1.777343, 1.782226, 1.787109, 1.791992, 1.796875, 1.801757, 1.80664,  1.811523, 1.816406, 1.821289, 1.826171, 1.831054, 1.835937, 1.84082,  1.845703, 1.850585, 1.855468, 1.860351, 1.865234, 1.870117, 1.875,  1.879882, 1.884765, 1.889648, 1.894531, 1.899414, 1.904296, 1.909179, 1.914062, 1.918945, 1.923828, 1.92871,  1.933593, 1.938476, 1.943359, 1.948242, 1.953125, 1.958007, 1.96289,  1.967773, 1.972656, 1.977539, 1.982421, 1.987304, 1.992187, 1.99707,  2.001953, 2.006835, 2.011718, 2.016601, 2.021484, 2.026367, 2.03125,  2.036132, 2.041015, 2.045898, 2.050781, 2.055664, 2.060546, 2.065429, 2.070312, 2.075195, 2.080078, 2.08496,  2.089843, 2.094726, 2.099609, 2.104492, 2.109375, 2.114257, 2.11914,  2.124023, 2.128906, 2.133789, 2.138671, 2.143554, 2.148437, 2.15332,  2.158203, 2.163085, 2.167968, 2.172851, 2.177734, 2.182617, 2.1875, 2.192382, 2.197265, 2.202148, 2.207031, 2.211914, 2.216796, 2.221679, 2.226562, 2.231445, 2.236328, 2.24121,  2.246093, 2.250976, 2.255859, 2.260742, 2.265625, 2.270507, 2.27539,  2.280273, 2.285156, 2.290039, 2.294921, 2.299804, 2.304687, 2.30957,  2.314453, 2.319335, 2.324218, 2.329101, 2.333984, 2.338867, 2.34375,  2.348632, 2.353515, 2.358398, 2.363281, 2.368164, 2.373046, 2.377929, 2.382812, 2.387695, 2.392578, 2.39746,  2.402343, 2.407226, 2.412109, 2.416992, 2.421875, 2.426757, 2.43164,  2.436523, 2.441406, 2.446289, 2.451171, 2.456054, 2.460937, 2.46582,  2.470703, 2.475585, 2.480468, 2.485351, 2.490234, 2.495117, 2.5,  2.504882, 2.509765, 2.514648, 2.519531, 2.524414, 2.529296, 2.534179, 2.539062, 2.543945, 2.548828, 2.55371,  2.558593, 2.563476, 2.568359, 2.573242, 2.578125, 2.583007, 2.58789,  2.592773, 2.597656, 2.602539, 2.607421, 2.612304, 2.617187, 2.62207,  2.626953, 2.631835, 2.636718, 2.641601, 2.646484, 2.651367, 2.65625,  2.661132, 2.666015, 2.670898, 2.675781, 2.680664, 2.685546, 2.690429, 2.695312, 2.700195, 2.705078, 2.70996,  2.714843, 2.719726, 2.724609, 2.729492, 2.734375, 2.739257, 2.74414,  2.749023, 2.753906, 2.758789, 2.763671, 2.768554, 2.773437, 2.77832,  2.783203, 2.788085, 2.792968, 2.797851, 2.802734, 2.807617, 2.8125, 2.817382, 2.822265, 2.827148, 2.832031, 2.836914, 2.841796, 2.846679, 2.851562, 2.856445, 2.861328, 2.86621,  2.871093, 2.875976, 2.880859, 2.885742, 2.890625, 2.895507, 2.90039,  2.905273, 2.910156, 2.915039, 2.919921, 2.924804, 2.929687, 2.93457,  2.939453, 2.944335, 2.949218, 2.954101, 2.958984, 2.963867, 2.96875,  2.973632, 2.978515, 2.983398, 2.988281, 2.993164, 2.998046, 3.002929, 3.007812, 3.012695, 3.017578, 3.02246,  3.027343, 3.032226, 3.037109, 3.041992, 3.046875, 3.051757, 3.05664,  3.061523, 3.066406, 3.071289, 3.076171, 3.081054, 3.085937, 3.09082,  3.095703, 3.100585, 3.105468, 3.110351, 3.115234, 3.120117, 3.125,  3.129882, 3.134765, 3.139648, 3.144531, 3.149414, 3.154296, 3.159179, 3.164062, 3.168945, 3.173828, 3.17871,  3.183593, 3.188476, 3.193359, 3.198242, 3.203125, 3.208007, 3.21289,  3.217773, 3.222656, 3.227539, 3.232421, 3.237304, 3.242187, 3.24707,  3.251953, 3.256835, 3.261718, 3.266601, 3.271484, 3.276367, 3.28125,  3.286132, 3.291015, 3.295898, 3.300781, 3.305664, 3.310546, 3.315429, 3.320312, 3.325195, 3.330078, 3.33496,  3.339843, 3.344726, 3.349609, 3.354492, 3.359375, 3.364257, 3.36914,  3.374023, 3.378906, 3.383789, 3.388671, 3.393554, 3.398437, 3.40332,  3.408203, 3.413085, 3.417968, 3.422851, 3.427734, 3.432617, 3.4375, 3.442382, 3.447265, 3.452148, 3.457031, 3.461914, 3.466796, 3.471679, 3.476562, 3.481445, 3.486328, 3.49121,  3.496093, 3.500976, 3.505859, 3.510742, 3.515625, 3.520507, 3.52539,  3.530273, 3.535156, 3.540039, 3.544921, 3.549804, 3.554687, 3.55957,  3.564453, 3.569335, 3.574218, 3.579101, 3.583984, 3.588867, 3.59375,  3.598632, 3.603515, 3.608398, 3.613281, 3.618164, 3.623046, 3.627929, 3.632812, 3.637695, 3.642578, 3.64746,  3.652343, 3.657226, 3.662109, 3.666992, 3.671875, 3.676757, 3.68164,  3.686523, 3.691406, 3.696289, 3.701171, 3.706054, 3.710937, 3.71582,  3.720703, 3.725585, 3.730468, 3.735351, 3.740234, 3.745117, 3.75, 3.754882, 3.759765, 3.764648, 3.769531, 3.774414, 3.779296, 3.784179, 3.789062, 3.793945, 3.798828, 3.80371,  3.808593, 3.813476, 3.818359, 3.823242, 3.828125, 3.833007, 3.83789,  3.842773, 3.847656, 3.852539, 3.857421, 3.862304, 3.867187, 3.87207,  3.876953, 3.881835, 3.886718, 3.891601, 3.896484, 3.901367, 3.90625,  3.911132, 3.916015, 3.920898, 3.925781, 3.930664, 3.935546, 3.940429, 3.945312, 3.950195, 3.955078, 3.95996,  3.964843, 3.969726, 3.974609, 3.979492, 3.984375, 3.989257, 3.99414,  3.999023, 4.003906, 4.008789, 4.013671, 4.018554, 4.023437, 4.02832,  4.033203, 4.038085, 4.042968, 4.047851, 4.052734, 4.057617, 4.0625, 4.067382, 4.072265, 4.077148, 4.082031, 4.086914, 4.091796, 4.096679, 4.101562, 4.106445, 4.111328, 4.11621,  4.121093, 4.125976, 4.130859, 4.135742, 4.140625, 4.145507, 4.15039,  4.155273, 4.160156, 4.165039, 4.169921, 4.174804, 4.179687, 4.18457,  4.189453, 4.194335, 4.199218, 4.204101, 4.208984, 4.213867, 4.21875,  4.223632, 4.228515, 4.233398, 4.238281, 4.243164, 4.248046, 4.252929, 4.257812, 4.262695, 4.267578, 4.27246,  4.277343, 4.282226, 4.287109, 4.291992, 4.296875, 4.301757, 4.30664,  4.311523, 4.316406, 4.321289, 4.326171, 4.331054, 4.335937, 4.34082,  4.345703, 4.350585, 4.355468, 4.360351, 4.365234, 4.370117, 4.375,  4.379882, 4.384765, 4.389648, 4.394531, 4.399414, 4.404296, 4.409179, 4.414062, 4.418945, 4.423828, 4.42871,  4.433593, 4.438476, 4.443359, 4.448242, 4.453125, 4.458007, 4.46289,  4.467773, 4.472656, 4.477539, 4.482421, 4.487304, 4.492187, 4.49707,  4.501953, 4.506835, 4.511718, 4.516601, 4.521484, 4.526367, 4.53125,  4.536132, 4.541015, 4.545898, 4.550781, 4.555664, 4.560546, 4.565429, 4.570312, 4.575195, 4.580078, 4.58496,  4.589843, 4.594726, 4.599609, 4.604492, 4.609375, 4.614257, 4.61914,  4.624023, 4.628906, 4.633789, 4.638671, 4.643554, 4.648437, 4.65332,  4.658203, 4.663085, 4.667968, 4.672851, 4.677734, 4.682617, 4.6875, 4.692382, 4.697265, 4.702148, 4.707031, 4.711914, 4.716796, 4.721679, 4.726562, 4.731445, 4.736328, 4.74121,  4.746093, 4.750976, 4.755859, 4.760742, 4.765625, 4.770507, 4.77539,  4.780273, 4.785156, 4.790039, 4.794921, 4.799804, 4.804687, 4.80957,  4.814453, 4.819335, 4.824218, 4.829101, 4.833984, 4.838867, 4.84375,  4.848632, 4.853515, 4.858398, 4.863281, 4.868164, 4.873046, 4.877929, 4.882812, 4.887695, 4.892578, 4.89746,  4.902343, 4.907226, 4.912109, 4.916992, 4.921875, 4.926757, 4.93164,  4.936523, 4.941406, 4.946289, 4.951171, 4.956054, 4.960937, 4.96582,  4.970703, 4.975585, 4.980468, 4.985351, 4.990234, 4.995117
};
const static byte chord_table[8][4]PROGMEM = {
 {  0,  68, 119,  205,  },//Maj
 { 0,  68, 119,  187,  },//Maj7
 { 0,  68, 119,  239,  },//Majadd9
 { 0,  34, 119,  205,  },//sus2
 { 0,  51, 119,  239,  },//minadd9
 { 0,  51, 119,  170,  },//min7
 { 0,  51, 119,  205,  },//min
 { 0,  0,  0,  0,  }//root
};

void setup()
{
 startMozzi(CONTROL_RATE); // :)
}
void updateControl() {
 //chord setting
 chord = (mozziAnalogRead(3) / 128) + (mozziAnalogRead(5) / 128);
 chord = constrain(chord, 0, 7);

 //inversion setting
 inv_knob = mozziAnalogRead(1);
 inv = (inv_knob  / 64)+ (mozziAnalogRead(4) / 64);
 inv = constrain(inv, 0, 15);

 if (inv_knob < 1020) { //when selecting wave , not apply
   switch (inv) {
     case 0:
       inv_aply1 = 0;
       inv_aply2 = 0;
       inv_aply3 = 0;
       inv_aply4 = 0;
       inv_aply5 = 0;
       break;

     case 1:
       inv_aply1 = 1;
       inv_aply2 = 0;
       inv_aply3 = 0;
       inv_aply4 = 0;
       inv_aply5 = 0;
       break;

     case 2:
       inv_aply1 = 1;
       inv_aply2 = 1;
       inv_aply3 = 0;
       inv_aply4 = 0;
       inv_aply5 = 0;
       break;

     case 3:
       inv_aply1 = 1;
       inv_aply2 = 1;
       inv_aply3 = 1;
       inv_aply4 = 0;
       inv_aply5 = 0;
       break;

     case 4:
       inv_aply1 = 1;
       inv_aply2 = 1;
       inv_aply3 = 1;
       inv_aply4 = 1;
       inv_aply5 = 0;
       break;

     case 5:
       inv_aply1 = 2;
       inv_aply2 = 1;
       inv_aply3 = 1;
       inv_aply4 = 1;
       inv_aply5 = 0;
       break;

     case 6:
       inv_aply1 = 2;
       inv_aply2 = 2;
       inv_aply3 = 1;
       inv_aply4 = 1;
       inv_aply5 = 0;
       break;

     case 7:
       inv_aply1 = 2;
       inv_aply2 = 2;
       inv_aply3 = 2;
       inv_aply4 = 1;
       inv_aply5 = 0;
       break;

     case 8:
       inv_aply1 = 2;
       inv_aply2 = 2;
       inv_aply3 = 2;
       inv_aply4 = 1;
       inv_aply5 = 1;
       break;

     case 9:
       inv_aply1 = 2;
       inv_aply2 = 2;
       inv_aply3 = 1;
       inv_aply4 = 1;
       inv_aply5 = 1;
       break;

     case 10:
       inv_aply1 = 2;
       inv_aply2 = 1;
       inv_aply3 = 1;
       inv_aply4 = 1;
       inv_aply5 = 1;
       break;

     case 11:
       inv_aply1 = 1;
       inv_aply2 = 1;
       inv_aply3 = 1;
       inv_aply4 = 1;
       inv_aply5 = 1;
       break;

     case 12:
       inv_aply1 = 1;
       inv_aply2 = 1;
       inv_aply3 = 1;
       inv_aply4 = 0;
       inv_aply5 = 1;
       break;

     case 13:
       inv_aply1 = 1;
       inv_aply2 = 1;
       inv_aply3 = 0;
       inv_aply4 = 0;
       inv_aply5 = 1;
       break;

     case 14:
       inv_aply1 = 1;
       inv_aply2 = 0;
       inv_aply3 = 0;
       inv_aply4 = 0;
       inv_aply5 = 1;
       break;

     case 15:
       inv_aply1 = 0;
       inv_aply2 = 0;
       inv_aply3 = 0;
       inv_aply4 = 0;
       inv_aply5 = 1;
       break;
   }
 }
 //setting chord note
 if (inv_knob < 1020) { //when selecting wave , not apply
   note1 = (pgm_read_byte(&(chord_table[chord][0])));
   note2 = (pgm_read_byte(&(chord_table[chord][1])));
   note3 = (pgm_read_byte(&(chord_table[chord][2])));
   note4 = (pgm_read_byte(&(chord_table[chord][3])));
   note5 = (pgm_read_byte(&(chord_table[chord][0])));
 }

 //OSC frequency knob
 freq1 = mozziAnalogRead(0) / 4 ;

 //set wave
 if (inv_knob >= 1020) { //inv knob max
   wave = (mozziAnalogRead(3) / 128);
 }

 //frequency setting
 voct = mozziAnalogRead(7) ;
 freqv1 = freq1 * pow(2, (pgm_read_float(&(voctpow[voct + 205 * inv_aply1 + note1])))); //ROOT
 freqv2 = freq1 * pow(2, (pgm_read_float(&(voctpow[voct + 205 * inv_aply2 + note2])))); //2nd
 freqv3 = freq1 * pow(2, (pgm_read_float(&(voctpow[voct + 205 * inv_aply3 + note3])))); //3rd
 freqv4 = freq1 * pow(2, (pgm_read_float(&(voctpow[voct + 205 * inv_aply4 + note4])))); //4th
 freqv5 = freq1 * pow(2, (pgm_read_float(&(voctpow[voct + note5])))); //ROOT

 switch (wave) {
   case 0://saw
     aSaw1.setFreq(freqv1); // set the frequency
     aSaw2.setFreq(freqv2);
     aSaw3.setFreq(freqv3);
     aSaw4.setFreq(freqv4);
     aSaw5.setFreq(freqv5);
     break;

   case 1://squ
     aSqu1.setFreq(freqv1); // set the frequency
     aSqu2.setFreq(freqv2);
     aSqu3.setFreq(freqv3);
     aSqu4.setFreq(freqv4);
     aSqu5.setFreq(freqv5);
     break;

   case 2://tri
     aTri1.setFreq(freqv1); // set the frequency
     aTri2.setFreq(freqv2);
     aTri3.setFreq(freqv3);
     aTri4.setFreq(freqv4);
     aTri5.setFreq(freqv5);
     break;

   case 3://sin
     aSin1.setFreq(freqv1); // set the frequency
     aSin2.setFreq(freqv2);
     aSin3.setFreq(freqv3);
     aSin4.setFreq(freqv4);
     aSin5.setFreq(freqv5);
     break;

   case 4://
     aChb1.setFreq(freqv1); // set the frequency
     aChb2.setFreq(freqv2);
     aChb3.setFreq(freqv3);
     aChb4.setFreq(freqv4);
     aChb5.setFreq(freqv5);
     break;

   case 5://
     ahSin1.setFreq(freqv1); // set the frequency
     ahSin2.setFreq(freqv2);
     ahSin3.setFreq(freqv3);
     ahSin4.setFreq(freqv4);
     ahSin5.setFreq(freqv5);
     break;

   case 6://
     aSig1.setFreq(freqv1); // set the frequency
     aSig2.setFreq(freqv2);
     aSig3.setFreq(freqv3);
     aSig4.setFreq(freqv4);
     aSig5.setFreq(freqv5);
     break;

   case 7://
     aPha1.setFreq(freqv1); // set the frequency
     aPha2.setFreq(freqv2);
     aPha3.setFreq(freqv3);
     aPha4.setFreq(freqv4);
     aPha5.setFreq(freqv5);
     break;
 }
}

int updateAudio() {
 switch (wave) {

   case 0:
     return MonoOutput::from8Bit(aSaw1.next() / 32 + aSaw2.next() / 32 + aSaw3.next() / 32 + aSaw4.next() / 32 + aSaw5.next() / 32 * inv_aply5);
     break;

   case 1:
     return MonoOutput::from8Bit(aSqu1.next() / 32 + aSqu2.next() / 32 + aSqu3.next() / 32 + aSqu4.next() / 32 + aSqu5.next() / 32 * inv_aply5);
     break;

   case 2:
     return MonoOutput::from8Bit(aTri1.next() / 32 + aTri2.next() / 32 + aTri3.next() / 32 + aTri4.next() / 32 + aTri5.next() / 32 * inv_aply5);
     break;

   case 3:
     return MonoOutput::from8Bit(aSin1.next() / 32 + aSin2.next() / 32 + aSin3.next() / 32 + aSin4.next() / 32 + aSin5.next() / 32 * inv_aply5);
     break;

   case 4:
     return MonoOutput::from8Bit(aChb1.next() / 32 + aChb2.next() / 32 + aChb3.next() / 32 + aChb4.next() / 32 + aChb5.next() / 32 * inv_aply5);
     break;

   case 5:
     return MonoOutput::from8Bit(ahSin1.next() / 32 + ahSin2.next() / 32 + ahSin3.next() / 32 + ahSin4.next() / 32 + ahSin5.next() / 32 * inv_aply5);
     break;

   case 6:
     return MonoOutput::from8Bit(aSig1.next() / 32 + aSig2.next() / 32 + aSig3.next() / 32 + aSig4.next() / 32 + aSig5.next() / 32 * inv_aply5);
     break;

   case 7:
     return MonoOutput::from8Bit(aPha1.next() / 32 + aPha2.next() / 32 + aPha3.next() / 32 + aPha4.next() / 32 + aPha5.next() / 32 * inv_aply5);
     break;

 }
}
void loop() {
 audioHook(); // required here
}

(Yeah, it's still a lot...)

Any assistance in resolving this would be greatly appreciated!