I had enjoyed my Line Magnetic 508 integrated to drive Lansche 4.1 speaker. Even with stock tube, LM 508 was better than retubed Rogue Cronus Magnum II with open and more dynamic sound. But I got bothered by somewhat bright presentation of LM 508 with stock tubes. When I had replaced stock SL7 tubes with 1944 RCS Nos SL7, sound got much more neutral. https://www.ebay.com/itm/Vintage-1944-RCA-JAN-6SL7GT-VT-229-Tube-Tests-Good/112606823278?ssPageName=... After few more tube rolling, I am using Sl7 Nos Brimar which I am happy with natural and transparent sound. https://www.ebay.com/itm/True-NOS-Gain-Tested-Brimar-England-CV1985-6SL7GT-Vacuum-Tube-Brown-Base/12... I also had replaced stock SN7 with Amperex SN7(Bugle boy) the sound got more natural with more bloom and details. https://www.ebay.com/itm/PAIR-OF-6SN7GTB-AMPEREX-TUBES-NEW-6SN7-NOS-NIB-Vacuum-Tubes-Bugle-Boy/26392... I had been happy with "Bugle Boy" for a while, this is a steal for the money. But after noticing right channel sounds slightly louder than left channel, I had decided to replace Bugle Boy with Bad Boy (1944 Sylvania VT-231 ) yesterday. Holy Cow! Sound got much more dynamic with wider soundstage. Also some siblance that I noticed after placing bells behind my speakers are gone. "Bad Boy" battered "Bugle Boy". Bugle Boy is a pretty good tube with nice details and overall balance but it could not match the dynamics and open sound of Bad Boy. As I like Bad Boy, I ordered one more tube as spare from the same source. This time he charged 125$. NOS SYLVANIA JAN CHS 6SN7GT (VT-231) chrome top Black 3 hole Tplates | eBay I had used Accuphase DG28 digital equalizer for room correction for 15 years. With Bad Boy in LM 508, the sound is so open and dynamic that it sounds more natural without room correction. Thus 100$ Bad Boy bumped Accuphase DG28 digital equalizer that I had paid 10K 15 years. 100$ Bad Boy brought more than twice improvement over that brought by Synergistic 150$ Blue fuse. This is the best 100$ that I had spent on my audio system. 100$ tube bumped 10K digital equalizer.