Speaks for sensitive, tinnitus-y ears?

IMHO you'd do much better getting the sound card out of your computer. Doing that conversion inside the environment of a computer has the potential to add all kinds of electronic grunge to your sound. Use either an external USB convertor, or a good USB DAC - convert the digits outside the computer. Also, make sure to rip your tunes as either Apple Lossless or WAV (uncompressed) format. If you are currently listening to MP3's and or downloaded music that could be the culpret right there. Compressed files certainly hurt my ears. As far as speakers go, look for soft-dome tweeters to cut down a bit on the harsh highs, but I really think my other suggestions will lead to more significant results.

Marco

I would check out small speakers from spendor. Though I don't own them myslef I have auditioned them and they have a very non-fatiguing quality.

I totally second what Marco said. Get the conversion out of the computer. Also, I'd get that mixer out of the path -- a decent external USB DAC (e.g., M-Audio, Presonus) will be all the preamp you need.

Thanks all, so far. I'm sure the sound card isn't optimal, but pro's used them for years with good results. I've had a usb m-audio, and the sound wasn't even close, even if it was cleaner. Unfortunately, I need a mixer, as I have all kinds of inputs to deal with. I would like to get a nicer mixer though, possibly usb/firewire, as you say.

My old polks weren't nearly as harsh though, so I kind of think the speakers might be the biggest contributor. I've never heard the spendors, so I'll try to look for a chance to listen to them. Are there others that are especially good that way? I'll remember the soft-dome tweeter part. I hadn't thought of it, but it does seem like metallic tweeters could be more harsh.
As far as itunes, I only import apple lossless. The eq in itunes is a good idea. I tried it on the treble reducer setting, and it is much better. At one time, I stopped using it for some reason (bad distortion, i think?), but I don't hear anything odd, so that might be an option for at least a while. Anyway, thanks again, kj.

Although I can't use the word "painful" I also don't like bright sounding speakers. The smoothest, that's my word for easy to listen to, speakers I've owned are Meadowlark Kestrel Hot Rods. These speakers truly get out of the way and bring no attention to themselves. Very mellow. They are however, floor standers. I've ried to figure out which speakers use the same Peerless tweeter without much luck. I believe the Sony SS-M3 uses it or a variation. Those Sonys were nice sounding speakers.
I highly recommend these if they fit. If not, definitely find a speaker with a soft dome tweeter. Good luck.