Sorry it should be TX-L55 and you can see the pic on my PC system. Released in 2003 back at the rage of class d receivers, it was basically an A9355 without Vector Linear and a simple 5.1 HT receiver. Same exact size as this new A-5VL and the watt rating I believe is the same. I just done the comparison a min ago but I've only been able to do it through the headphone as it's 1:30AM. The L55 still has the smoothness of the A9555 and A9755, basically an amp that audiophiles would love, but the 5VL is the cold analytical beast that some reviewers mentioned. It's by no means bad. It's just far more accurate and detailed to the signal without any additional decay or air or involvement that we are used to hearing even when we're talking about class d amps! The result is the same whether it's using the digital input or not. You would use this amp to do critical listening, not so much on easy listening.
While the rest of Onkyo's class d amps cater to the audiophile crowd, the character of this amp fits best connected to a PC or iPod, thus the digital coax input. In fact, it plays rap, metal, rock and other hard musics noticeably better than the other Onkyos. The price, sound, features, and compact size put this amp directly in that market category. The only reason why many of us are disappointed with the sound is simply because having been exposed to the A9555 we expected it to have the same liquidity, air, and soul while maintaining accuracy. Only when we look at the market segment of the A-5VL then things start to make sense. Then again this could be where Onkyo is heading with their next gen class d modules. Regardless even for a class d fanatic like me, this amp is most likely going to end up in my PC, office, or kid's bedroom. But tomorrow I'm gonna put it against my Cary ICE based separates and see if it actually matches better with my Newform ribbons. Hopefully it can fix the ICE's downsides by adding more top end sparkle and clearer more forward vocals. Oh did I mention the build quality that rivals Bryston B60?
In regards to your need to fit it in a rack, the top vent gets really hot as there's only about 1cm to the top of the biggest capacitor, but I wouldn't worry about it blowing up or anything.