I've owned the 3A Sigs and the SP9 MKII (and MKIII). Neither caused any distortion on my vinyl. What did cause the distortion you describe was bad cartridge setup, especially zenith.
The Electro Harmonix tubes were ho-hum IMO. In the MKII I liked Telefunken ECC88 but in the more detailed MarkIII I liked the E88CC.
The 3A Sigs were sensitive to cables for sure. I had cheap Monster Powerline 2 and going to Acoustic Zen Satori reduced glare dramatically. Also, reducing "midrange glare" is a function of the tweeter control, not the midrange control, so a heads up on that. Good Luck!
The Electro Harmonix tubes were ho-hum IMO. In the MKII I liked Telefunken ECC88 but in the more detailed MarkIII I liked the E88CC.
The 3A Sigs were sensitive to cables for sure. I had cheap Monster Powerline 2 and going to Acoustic Zen Satori reduced glare dramatically. Also, reducing "midrange glare" is a function of the tweeter control, not the midrange control, so a heads up on that. Good Luck!