ATI AT1506 vs Newer Models

I currently own an ATI AT1506 that I use to drive 3 Sonus Faber Concertos in bridged mode. The surrounds (Klipsch bookshelf speakers) are driven by a Denon 4802. The system sounds better in bridged mode than it does when all 5 speakers are driven by the ATI. I'm thinking about a second amp (ATI 1504 bridged) to drive the surrounds, but I'm wondering if I should just sell the 1506 and move up to one of the newer, higher output models. Is the bridged setup the best way to go, or am I losing (or hurting) something in this setup? The 1506 is the only amp I've ever owned and I'm hooked on it because it my system sounds so much better with it than without. Are there other amps that offer the same or better sound for the price? Any feedback would be appreciated.
I have owned the ATI 1502 for a few years and recently decided to do what afew people had recommended--to bridge a pair of these. The result I felt was underwhelming and fatiguing. This seems to contradict what you are saying and may reflect my small room, speaker choices....I have a 1502 which I will soon put up for sale as I moved on to a Pass labs aleph 3 (30wpc which is plenty for my room. I do love this amp and am going to miss it. I dont know of anything comparable at the pricepoint, and have not tried the new ones. Good luck
Thanks for the feedback. I guess I should have mentioned that my setup is in a 1+1/2 story room. 18' by 12', hardwood floors, no curtains, sparcely furnished. My reciever is a Denon 4802. Without the ATI, I had to turn the volume up to "feel" the music. Below some threshold (that my wife enforces) I couldn't hear the detail that I want to hear. With the ATI driving all 5 speakers, the detail is there without having to turn the volume up above the wife's limits. When bridged, I seem to hear even more detail at even lower volumes. I'm no audiophile, but when I read articles where people write about imaging and soundstage, I wonder if I could be getting more from my speakers with a more powerful amp. Then again, maybe I should just shut up and be happy with what I already have.