new at this...which amp?

150wpc should be enough power, and changing the power amp is one of the last things I'd do - negligable if any return on $ spent. Adcom's are OK, and adding power would only exacerbate the situation.
Brownsfan has a good handle on a good way to tame room / system interaction. If you look at the pictures of my system you can see that wall treatments are used heavily to tame the sound - I can go MUCH louder on my system than before before it glares at me from room interaction. Spending $200-$400 here will make a ton of difference.
Another place to look is your front end - what's your CDP and DAC? Harshness and grain are typical digital factors. You may not notice it as much at lower volumes.
Don't get carried away on cables yet either. sure I'd do somethuing a bit better in interconnects, but again, value for $ spent will be room treatments and digital source components. I usually vote for Transparent cables, as I think they affect the sound the least - ever notice they're never mentioned in cables to make the sound change threads? But even so, cables are a small change compared to the stuff above.
Don't think about changing amps until you have the things above considered.

I second the post from brownsfan. The room is very important-taming resonances, toning down harsh reflections, taming bass modes, etc. I had an ADCOM amp and sold it. I thought it was too brilliant on the high end, and that was a "soft" room. I really don't think its a power issue, but more of an amp issue. I bought Outlaw M200s for each channel and they really "disappear". I don't perceive any harshness or ear fatigue. I think there are many amps in your price range that you would be happy with, but, again, you may want to work on your room first. Good luck!

Not so sure it is the room. This system has been in three rooms and had the same problem.
Muralman1, is that to say that Adcom is not good stuff? I have a Rotel 200 by 5 available to me at a good price. Is that a better choice than the Adcom 300 by 5? I will look at that review for the Signature.

Adcom is decent stuff - I doubt whether you'd hear any significant difference with a Rotel. Amps are not where your problem is. What's your front end?

Yes, Adcom is good suff - just good. Like Tgrisham says, it is exacerbating the brightness in his system. The H2O is in a class of it's own. My last solid state were Pass Labs X600 monos. It was no match for the H2O. The Adcom isn't on the same page of either amp. A single H2O S-250, at $2K is all that's needed power wise for any speaker.

The Radio Shack interconnects are big culprits as well. For ultimate clarity in speaker cables, try Speltz's Anti-Cable. It's as cheap as Radio Shack, and better than - well, read the testimonials.