Right now
Audio Advisor has the Cambridge 640A v2 on sale/closeout for $399.99, and you can get the factory-refreshed Onkyo A-9555 from
Accessories4less with a 1-year warranty, also for $399.99. Deals on the Onkyo are drying up fast and accessories4less is running low on stock.
These two are definitely on the short list for sub-$1K integrateds. The Onkyo is competitive at its list price of $799, but sells most places for $699. At $400 or $500 it's just killer, incredibly clean, dynamic, and powerful sounding. It requires about 100 hrs of break-in.
The Cambridge is line stage only, but has preamp outputs. The Onkyo has a good built-in phono stage, but no pre-outs. I like them both but have a personal preference for the Onkyo.
I have been an audio enthusiast for 40 years and have owned a lot of vintage and used gear, and sold new and used retail in the '70s. But the Onkyo has shifted my paradigm: I'd now rather have the Onkyo A-9555 (which I do) than any used $400-500 amp that I can think of. I like it better than anything near the price, new or used, from Parasound or Adcom.