Airtight ATC5s pre VS Thoress Full function pre

It all came down to these two before making my final decision to buy my end game pre amplifier. My dealer brought me over these two pre alongside a consolidated audio SUT for a home demo. However Thoress started to develop a noise when it was set to play mc phono stage. It was totally fine at the dealer’s place. We opened it up anyway just to see if the noise would go away if we change the tubes, but it did not work out. However noise was not that big of an issue because when we played the music, the noise coming out from the tweeter was negligible. I gotta say Thoress was good. Lot better than Supratek and Cary. But Airtight is just in a different league. Jaw dropping stuff..