Warm, clean tone with creamy overdrive! PREMIUM selected quality for the most demanding amp stages. This tube works greatly for warm clean tones and creamy overdrive. We recommend this tube for the 1st gain stage and as input tube. It upgrades 12AX7A and ECC83 tubes and replaces E83CC tubes. The HIGHGRADE Selection is the tip-of-the-top quality at the lowest noise (microphony, hum, hiss) level. Typically only 0.5-2% out of the whole production of this tube meet the HIGHGRADE requirements. The TAD 7025 Highgrade can replace any ECC83, E83CC, 12AX7, 12AX7A, 12AX7M, 12AX7WA/WB/WC/LPS/EH, 5751 or 7025. Q: When does a preamp tube become a Premium Selected tube? A: All preamp tubes labeled Premium Selected have passed the following tests: Low Noise Test Microphonic Test Gain Test Sonic Tests Shock Tests Listening Tests Balanced Output Test