EDIT: After using this preamp in many real life situations I noticed a problem with hum. I've added this to my review and adjusted my ratings.
I wanted an alternative to my EBS Valvedrive for gigs when I can't bring my own amp. Basically as a backup if the provided backline is either a poor quality solid state amp or non-existent (DI only).
Pros:
-Good clean tone.
-Nice tone controls with sensible frequency points.
-Dry/wet blend for the drive circuit is useful.
-Headphone out is great for practise.
-The external build quality seems to be sturdy enough for a life on the road.
Cons:
-I get a significant amount of hum with some basses unless I connect this preamp to grounded equipment. With some basses the hum is barely noticable but with others it is quite loud. These are basses that are dead quiet with other equipment. I can only assume this must be caused by the fact this Markbass preamp comes with an ungrounded electrical plug (touching the chassis of the preamp or any metal parts on the bass that are connected to ground will silence the hum). If you're plugging into an amp this won't be a problem as the amp will be grounded but this preamp is also marketed for recording (it has digital outputs for this). If you're connecting the preamp directly to an audio interface that is either usb-powered or has an ungrounded electrical plug (most interfaces do) and then use a laptop that also has an ungrounded plug (most consumer level laptops do) you have a problem. Bascially, if any other part of your signal chain is grounded you'll be fine. If not you may experience excessive hum.
-Although the clean tone is good it's not really THAT much better than going through any good quality on-stage DI-box. I'm not sure the clean tone alone is worth the price.
-The tube circuit sounds absolutely horrible when driven into even just a tiny bit of distortion. Forget about anything resembling a real tube amp driven hard, this pedal will only give you a fizzy, thin distortion. There is no gradual increase of distortion. You either get a nasty fizzy distortion or nothing. If you try setting the gain at the edge of distortion you will get a nasty, fizzy tone when digging in hard and a clean tone when playing softly. Also, the distortion feels like it sits "on top" of the clean tone, rather than being a part of it. Absolutely horrible and utterly useless.
-The drive section doesn't seem to go through the tube circuitry at all. It sounds like a rather muddy, cheap distortion pedal in one setting and a scooped, boomy mess in the other setting. The "distortion pedal"-setting can be useful for thickening the tone when blending in just a little bit with the clean signal but that's about it. I had expected more at this price.
-The three-way "preset" tone switch didn't do much for me. I only like the tone of this pedal in flat mode and find the other two settings "overcooked" and rather useless.
-The effects loop seems to be in parallell??? This could have been somewhat useful if it at least had a dry/wet blend knob but unfortunately it doesn't. It seems to be set for approximately a 50/50 blend which is completely useless for most situations. I honestly don't understand the idea behind this design. Effects that need to be blended with the dry signal (like reverbs) normally have an adjustable dry/wet setting anyway and a preset dry/wet mix in the effects loop is an almost unbelievably stupid design.
-If you have any plans about rolling tubes, forget about it. The tube seems almost impossible to replace. It's positioned in a way that won't let you get a good grip to pull it out and it also sits on a small circuit board that seems very fragile. I guess you MIGHT be able to pull the tube out somehow but I would be worried about breaking the connections to the main circuit board. It seems very fragile and the preamp is clearly not designed with tube replacement in mind. Not that I expect a diffent tube to make much different in a circuit like this but it would have been nice to at least have an opportunity to try.
-Personally I don't understand the point of the digital outputs. It's pointless for use on stage and I don't see why anyone would need it for recording either. Anyone who owns an audio interface will have digital converters already. What's the advantage of using these digital outputs? I strongly doubt if the converter in this pedal is of better quality than the converters in even the cheapest audio interfaces available today. I feel like I'm paying for something I don't need here, and I suspect most bass players who might be interested in this pedal won't need these digital outputs either.
To sum it up: If you want a preamp with a good CLEAN tone and nice (but very basic) tone controls, this pedal might be a good choice. However, if you want something that can give your tone a bit of dirt without sounding fizzy or if you need a usable effects loop or if you want to be able to change the tube without the risk of damaging the circuit board... Forget about it. You won't find these things here. This pedal may seem to have a lot of features but most of them are pretty useless.
I'm only keeping this pedal because of the headphone out. It's nice for silent practise and the hassle of a return (customs paperwork, VAT refund) just isn't worth it. I would definitely not buy it again though.
