I have the avantgarde uno's as well with a Cary 300sei and understand what you are saying. I did some checking with my local dealer, and he recommeneded the Quicksilver horn top amps. Quicksilver makes a tube monoblock amp that is suppose to be super quiet for horns but produce more power than the cary 300sei.
Also, he recommended a low power push pull amp such as the copland integrated, or pathos integrated. He said by giving the avantgarde's 50 watts of power in push pull should really light these up. I am in the process of changing my 300sei out as well. It sounds great as a good quiet amp for jazz, classical, etc. but do not really perform as expected.
Hope this helps,
Steve
Also, he recommended a low power push pull amp such as the copland integrated, or pathos integrated. He said by giving the avantgarde's 50 watts of power in push pull should really light these up. I am in the process of changing my 300sei out as well. It sounds great as a good quiet amp for jazz, classical, etc. but do not really perform as expected.
Hope this helps,
Steve