Anyone who wants to transform their solid-state amp into a tube amp should try the TubeWave setting of PS Audio
MultiWave II. It made it warmer and faster than Mullard CV4003/12AU7 tubes and without the rolled-off highs and harmonic distortion.
MWave 4 (P-4) setting gives the best performance for power amps but it's also the most fatiguing because the transients are too fast, I can only last 5 minutes before I start feeling sick. But when changing to TubeWave I can listen 12+ hours straight!