Ken, I am still using the stock Ei tubes, I just keep forgetting to order new ones! Honestly I think the stingray in triode is overkill with the 99's the volume knob is like an on/off switch, there is really very little control! I am thinking of going with a lower power amp. If I don't do that I have spoke with the service guy at Manley and he told me how to remove the detents from the volume to gain better control, but it will take several hours and I'd rather be listening then working on my amp :) I've said it before and I'll say it again, this amp in triode has NO right sounding as good as it does, I am amazed how good it is for how little it costs - I am not complaining.
What are your thoughts between UL and triode now that you've tried both?