Hi,
Just a quick note here that the C28 has quite a number of channel specific dials across the top where one channel may be turned completely off. If your friend isn't familiar with this model and if his C28 happens to be in a wooden case then he may not know they are there. You can press the panloc buttons in and pull the preamp out a bit to access them. Be sure all dials are turned all the way up. Just mentioning this because I thought one of my speakers was a bit soft but I checked these dials and found that one was turned halfway down for some reason. Most people seeing this are probably saying "duh" but I'm mentioning it anyway because I'm a little slow sometimes and I listened to a muted right channel for about a week before it occurred to me to check those dials out!