J135 What has been your experience with the Onkyo?
Can you name some characteristics that you enjoy?
Any area the amp is lacking for you?
I've owned an A-9555 for nearly 4 years and it anchored my LP-based 2-channel system for nearly 3 of them. I agree with the other respondents that this amp is very hard to beat at either its street or used price. I got mine new from Amazon in silver for $474.
Compared to other $500 integrateds, it has several advantages: 1) It seems that most ~$500 integrateds have some midrange glare, are limited in bandwidth (and speed) to tame this glare, or lack either power or refinement. The Onkyo manages to give you lots of power, lots of speed, a lot of instantaneous peak current (which makes the amp sound more powerful playing music than it measures on the test bench), nice transparency and clarity without sounding harsh or edgy. I found the amp to be very neutral and musically engaging throughout the time I used it.
When you first get it out of the box it's going to sound sterile and edgy. Have faith. It needs at least 100 hours to burn in. I tuned in an FM station and ran it all the time at low volume when not playing music through it. At about 4-5 days it started settling in.
Leave it on all the time, at least in standby mode. Accd'g to reviews I've read, switching amps need 10-12 hours warmup to sound right. In standby mode the Onkyo is very "green," drawing only 1/4 watt.
Try out some different power cords. That's another thing switching amps are reputedly sensitive to. When I tried 3 different cords I heard three different presentations, though maybe I needed to let each power cord burn in too. Anyway, at that time I settled on a PS Audio from about 6 yrs ago. Now I use a Zu BoK to match the Zu interconnects and speaker cables I rewired the system with 2 years ago.
The amp has lots of I/Os. I think you can plug up to 7 devices into it, and it even has a built-in phono preamp. I found that the phono section was very smooth and excellent with inner detail, but didn't have much slam, so I used an outboard phono preamp.
I wish it had pre-out/main-in jacks, or at least pre-outs, but it doesn't. Even so, I used it as a line stage by running a headphone-to-RCA cable out of the headphone jack. It is a surprisingly good line stage.
The speaker terminals only accept bare wire, pins, or bananas. The amp gives back so much, though, that I consider it well worth ordering your cables with bananas. I even bi-wired by running two sets of banana-terminated cables to the LF and HF inputs of my speakers. Sounded very good and the amp had no trouble driving it that way.
The fit and finish are excellent. The amp's buttons, switches, and controls have a luxurious silky feel. At 28 lbs. it's heavy for an 85 wpc switching amp because it's a hybrid and uses a full-size linear power supply.
In summary, the thing I like most about this amp is that it provides more power, bandwidth, and clarity at this price point than good-sounding competitive models (e.g., Rega, Marantz, Cambridge) without sacrificing refinement, smoothness, transparency, or musicality.