Sounds like your amplifier is the responsible party.
This seems like a reasonably priced tube integrated:
http://www.audiogon.com/cgi-bin/cls.pl?intatube&1293064678
Here is a solid state amplifier which was not fatiguing to me and is a bargain of a price:
http://store.virtueaudio.com/product-p/vrtu-ia-vaone.2-pbf-1.htm
The Virtue guys have a good return policy, so if it doesn't solve the problem, return it!
This seems like a reasonably priced tube integrated:
http://www.audiogon.com/cgi-bin/cls.pl?intatube&1293064678
Here is a solid state amplifier which was not fatiguing to me and is a bargain of a price:
http://store.virtueaudio.com/product-p/vrtu-ia-vaone.2-pbf-1.htm
The Virtue guys have a good return policy, so if it doesn't solve the problem, return it!