This is the only MXR pedal I haven't been thrilled with. It does everything well, but has a bit of hiss. I use a (provided) SansAmp DI on a regular basis, and like it (plus it's dead quiet), but was looking for something smaller and less expensive to sit on my board. Feature-wise, the MXR does everything I need and sounds great. Like all newer MXR pedals, the LED is super bright.
 I bought this used, and the hiss was very noticeable. I sent it to Dunlop to have it looked over and brought to factory specs for $50. When I got it back, the hiss was quieter, but still there. A note with the pedal indicated that it was within factory specs. I still use it, but when I'm where the SansAmp is, I use that.
- Pedal Type:
- preamp + DI
- 9V battery or standard DC adapter
- EQ / Controls:
- input & output volumes; bass, mid (parametric), treble; ground lift, direct output pre/post, bypass footswitch
- midrange frequency selector is a 5-way switch
The Bass Preamp features separate INPUT and OUTPUT level controls and a 3-band EQ section with sweepable midrange-from 250hz to 1khz-for extensive tonal flexibility. It's all delivered super clean with high headroom thanks to our own Constant Headroom Technology, and you can use the PRE/POST EQ switch to set whether or not your Direct Out signal is affected by the Bass Preamp's EQ section. And of course, the Bass Preamp features a GROUND LIFT switch in case you encounter ground loop hum.
The Bass Preamp is factory preset to operate in ¼" out buffered bypass and Direct Out active. For players who only want to use the ¼" out, there are two internal switches that disable the Direct Out and ¼" out buffered bypass for true ¼" out bypass mode.