Review on 🔊 FX AUDIO Tube Preamp: NE5532 Replaceable Tube and OP Amp Chip Mini HiFi Stereo 6K4 Vacuum Tube Buffer Preamplifier - Bass and Treble Control - RCA Cable Included for Amp/Active Speaker by Lisa Hedberg

My system: NAD C162 preamp, Acurus A250 power, Klipsch R-610F After comparing to NAD I will use this one because it sounds a bit nicer. I would like to share my experience in the following way. I wanted more control for the high end and I'm happy with this 03 tube because it has more high end than the C162 (maybe it's because the C162 is old and not pumped up). I bought GE 5654W tubes for sound comparison and found no improvement over 6K4. I get a slightly thicker voice and slightly louder volume with 5654W, but that's not an improvement for me. There are both disadvantages and advantages. I hear an annoying popping noise when turning this preamp on/off. Turn on the power amp and turn off the power amp before turning off the preamp. There are red LEDs under the tubes and I hate to see that because it makes this preamp look fake. The right channel is louder than the left channel at very low volume, 23dB difference, e.g. 57dB versus 55dB. It is balanced when the volume is turned on. is crumpled, the difference is less than 1 dB, e.g. 65 dB vs. 64.5 dB. I found this by playing a sine wave from YouTube. I can only turn the volume knob clockwise up to 20% because my 250w power amp is getting too loud. a problem for lower gain power amplifiers. I may change the potentiometer one day to solve this problem. Anyway, I like it very much.