Tube change.

@jbsqg I have the Triangleart TA-350m mono’s. 8 Kt-88 tubes(can’t use 6550) 3- 6ns7 tubes driver 1-6sl7 rectifier tube. I was told the power tubes on the amps would make the biggest impact on sound quality. SE of course makes no guarantee but states customers report a significant improvement in almost every area musicality, soundstage, bass, midrange when using their tubes. Even though expensive considering it because it’s still less than upgrading to another amp and less hassle than trying to sell mines. I’m very pleased with my amp but this little voice inside me keeps saying What If?

@axpert I have the Triangleart mono’s mentioned above.

Triangleart L-200Mk 2 preamp + Rhea power conditioner 

Emm labs transport and dac, Trenner&Friedl Isis speakers

I've had a few Sophia Electric tubes myself and they generally sound excellent. Their Blue Glass 6SN7 might be my absolute favorite.

@sidog1460 

You don’t have your amps plugged into your Rhea PC, do you?

Wow! What beautiful amplifiers! Sorry that I thought that they might be VTL's as your's seem to be in another league altogether, at least compared to lower-end VTL's. So all I can say is keep playing with input tubes. Apologies for rambling on about the wrong amps.