I'm using the groove tube mullard reissues too. They vary in sound from one tube to the next. Some sound unbelievable, others can be thin sounding or fuzzy sounding. I went through five tubes to find three to get the sound I wanted. I tried out RCA blackplates, Telefunken smoothplates, plus the originals. You could take the best properties of all these tubes and combine them into one tube and the Groove Tubes is still better. The originals compete well against the NOS tubes, but its no contest against the groove tubes. It's important to get the good ones. Combine them with a wilson benesch tonearm and the accuracy is amazing.