Bel Canto Dac 3

That's an interesting observation and I am considering the DAC3. Is it possible that your unit is not broken in as yet where tubes generating more heat can break in faster? I am looking at simplifying my system as I only run digital and although most people indicate that it is better to have a preamp I would prefer to sell my preamp and put the cash into a better DAC with volume control.

Another option to try might be the Grace Audio M902.
http://www.gracedesign.com/products/m902/m902.htm
I am happy with my Lavry and had to cut the cost of my system at some point but next time around this might be the one I'll go for.

Regarding cables, there is a lot of debate as to how much of a difference they make. Recently I changed my speaker cables and it's made a massive change. My amp was lifeless before but there is only so much trial and error we can do otherwise it becomes a costly habit.