Clipping

+1 bsmg! Loud rock (Zeppelin, Sabbath, ZZ Top ...) is recorded and meant to be played back LOUD! Sounds like you are clipping your amp. More power needed - or more efficient speakers!

My error forgot to mention cary Audio SL-80 F1 Signature tube amp 25 -50 watts with 84 db Fritz Carbon 8 MK II speakers.  This record is 180 gram remastered.  Thanks for your replies. Will turn it down but it not really that.loud with volume knob at 11 o'clock

Can’t find Fritz Carbon 8 MK II online. Need to know the impedance as well as the 84dB spec.
+1 roberjerman.

Also, have you tried different a different load setting on phonostage?

phil, turn the volume down. If you still hear the distortion it is most likely your cartridge miss-tracking in which case you have to go over your tone arm set up. Koetsu's are not the best tracking cartridges. It could also be the cartridge overloading the phono amp which I doubt unless there is perhaps a bad tube or the phone amp overloading the preamp. If the distortion goes away with lowering the volume then you are most likely clipping your amp. But you said the volume was not that high so I have a hard time with that theory. 

@lowrider57  did not reread my email. Speakers are Fritz Carbon 7 MK II speakers..88. Db