Best bargain integrated amp?

I'm in the market for a new integrated amp. I currently own a Cambridge Audio 640A, but am begining to notice its short commings. I'm looking for a more refined amp with more power. I listen to mostly rock, jazz, acoustic guitar stuff: Leo Kottke, Nick Drake etc. in that order.

I would like to go second hand and spend no more than $700.00, and I guess my question is will I notice a considerable improvement sound quality with a second hand amp of this price?

I'm interested in the Odyssey Audio Cyclops but have yet to find it used. What other units should I consider?

My system:
Speakers: Acoustic Energy Aelite 2
CDP: ShengYa CD-s10 (tube)
Interconnects: Kimber Kable Timbre
Speaker Cables: PS Audio X-Stream Plus

Thanks for the help.