I read reviews of those whom xpa5 allegedly helped. Hence vought it too and hoped it would work fine. But it did not. Not sure what it was but it was obvious. Avr sounded better. I had to pay for return because technically it was not faulty as dealer said. Then I tried mca 525 and it was completely different from xpa5. But it sounded the same as my yamaha without and it helped me with distortion i had with a860 especially in multichanel stereo.. Not sure whether it was an issue with xpa5 or its incompatibility in some way with avr or something else. Would be great to know the reason to avoid such returns in future.\n\nAlso wonder, what was wrong with OP's Monolith as in personally i could not hear the difference between it and mca525.\nMany people reported night and day better when they added their xpa-5 to their avrs. I have no idea why you hear the crappy sound with it, 1 dB different in gain won't make such a difference. Input impedance, if on the low side, when matched with preamps that have relatively higher output impedance, could result in audible effects. That does not appear to be your case though.