the problem with Amazon is that you need a lot of traffic to make it working good. That's because the low advertising rates.
but if you have the traffic, go on! and let us know your progress, so we can study a couple of stats.
Always do your own tests, I only know of 1 message board where I trust the opinions of (most of) the members there (not WF sorry ), and even then if I feel it's a good idea I go for it and test it myself.
People who are surfing the web for music are looking for new amusements and aren't really in the mood to buy books/appliances/and whatever else amazon sells.
The T shirt ads might do better if they are creative T shirts that appeal to your target market.
But, before you do trial and error, do you know who reads your site? their age? demographic? psychographic? etc? that'll help.
It depends... is there anything on Amazon that you can promote to your visitors that is targeted enough? If so, I see absolutely no reason why you couldn't make a good go of it. Plenty of other affiliates have success with Amazon!
I highly doubt that if you can't sell with Amazon you will with other programs. Rates are not a problem. With 10 sales a day you are like at 6.5% right ? But let's say your other program conversion rate 1% for a program which pays 13%, more than sure that with Amazon it will be 2-3% or more. Isn't it ? Cause of brand etc. I am not even talking about inventory.