I have read a lot of bad reviews about the Denon DCM 290 and 390 changers, bad reliability, worse service, but they have Burr Brown DACs - the 390 has a 20 bit DAC. No other changers on the market have these DACs that I know of - Sony uses Analog Devices, Marantz - Cirrus Logic. I am not sure what Yamaha uses. IMO from what I have read, Burr Brown is considered among the best.
I currently have a 15 year old Yamaha changer. It has no digital output, and I am in the exact same boat as the OP. It sounds OK, but I have a 15 year old yami reciever, so who knows what compromise in sound is amp- or changer-based.
IMO, if you're going to spend +/- $500 on a changer, buy an airport express, a MF V-DAC and a decent mini-toslink cable, if you have an iPod, you already have a ton of stuff ripped. Install AirTunes and stream to the airport express, if you have a wireless network in your house. I recently re-ripped everything to .mp3 320, which was an upgrade from what I had. Hard-drive space makes it difficult to go %100 lossless, so my tracks have to earn the right to be ripped in AIFF or WAV or ALC.
I oscillate between going PC audio and just getting another changer, I'm still saving up. I have been looking at the changer market, and you will occasionally see a used Rotel RCC-1055 come on Audiogon, Craigslist or eBay, and they go fast. NAD made a changer once-upon-a-time, the 517 I think, but I never see it used. California Audio Labs also made a changer that most think is the best sounding changer ever made. Also some of the old Sony ES changers are very well respected. If you bought one of these and it broke, where would you get it fixed? They aren't cheap, even used, and not under warranty!
The thing I like about the Yami changers is you can see all 5 discs at once, no need to rotate the carousel to change CDs. Sony's tray only comes partially out. I am cautious about the Sony and Yami changers just because their upper level 2-channel gear is not very well liked by the audiophile community. Denon has gone almost completely HT these days, so what would they know about a good quality changer? Apparently they know Burr Brown, which is good enough for me. Sony helped invent the medium, so you would expect them to produce a great product, and their current SACD changer is tempting, internet reviews are generally good. Would you also expect current changers to sound better than older ones because of advancements in D to A technology?
Forgive my rambling, just some thought to toss into the mix.