The TAD Selected 5751 is our first choice for noticeably improved clarity, smoothness, and a true vintage tone character for most guitar amps! There will still be plenty of gain - so if you own a high-gain preamp that does not have these classic crunch characteristics, the 5751 tube will work wonders. In hi-fi preamps and CD players, the TAD selected 5751 will lower the noise floor and sound smoother and clearer than many 12AX7 tubes. Especially this low-noise tube is recommended for best clean tone with big bottom, warm midrange and silky top end. Performs great for HiFi too! Replaces any 12AX7A/WA, ECC83, 7025 etc.