adcom 5006?

Hi, I'm looking to buy a used amp shortly. I have Klipsch kg3.5 speakers. I had an adcom 5400 on them at one time(it was my roommate's amp). I would like to move up from that though. I was looking to get a 5500 maybe. But I saw the 5006 and it caught my eye. It says you can bridge it run 175x3. By doing this, does it force the amp to 4ohm? How do you go about bridging it. The only expierence I have with that was from car audio where you wired the one - to one channel and the + to another channel. Also, does running 4ohm vs 8ohm cause any loss of sound quality? Thanks.
Nope buy the used Adcom 555 here on Agon and have them modified. I know someone if you cannot find someone near you. The original 555 was designed by Nelson Pass or Pass Labs and not too amny people know that. I have a friend with one and while not in the high end camp sonically is pretty great sounding after the mod and some chump change to buy and mod it.
How much of a difference would you say there is in a 5500 vs 555 with out the mods you talk about? What do they do to them and how much does it cost? Are there any other amps in that price range that I might should consider? Thanks!!!!