The WE 101D tubes are an improvement but probably not what you are looking for. You can send it to me for a major upgrade and it will be a major upgrade. Tubes can change the flavor of the sound yes but for a bigger improvement, better capacitors and resistors will be more beneficial. My company builds 101D audio tube products as well as 6SN7 tube products so we are very familiar them. We can even improve your Supratec.
Happy Listening