I wouldn't let tube usage stop me from listening ever. They're SUPPOSED to be disposable! The way I look at warm up time is: even cold it's likely damn good sounding. After an hour it's magical and after a few hours downright beguiling. I'm talking about a Dynaco ST-70, with a pair of Dahlquist DQ-10's; as much as I like this system, it's nothing fancy, and I'd bet your system sounds much, much better. I'd just get depressed even trying to quantify how much better I bet your system sounds- enjoy it. If you're determined to make a change amp-wise though, I've had both NAD and Luxman. Nothing against NAD- it was better than I expected it to be, and if it was all I had I'd be totally content. I still have Luxman- and when I hook it up- I LOVE it. Every time.