The older Cambridge gear such as the various A1, A2 and A3 amplifiers were designed by Michael Creek, so they had the same sound signature, they were just made in Asia instead of the UK which allowed for a lower price. Not sure about who designed the current crop of amplifiers, other than the T500 tuner is a toned down copy of Mike Creek's T43 tuner which is also made in Asia instead of the UK. The phono upgrade in the Cambridge is also a Creek creation.
The Creek gear will costs you double what the Cambridge gear cost (new and used). You do get what you pay for between Cambridge an Creek, however I still consider the A3i a total steal used. Two sold on eBay in the last month for about $225. You won't find a Creek for that price that is 60 watts and comes standard with phono. See the reviews at AudioReview.com
BTW, I have both a mid-fi Onkyo Integra audio only receiver at work and a Cambridge A3i amp in a bedroom system. The A3i is much better. I also do think the A3i sounds better than the A500.