I've got a little bit of cash spare and I'm thinking of getting the DigiTech Bad Monkey as my OD pedal, but I was also wondering if it could boost my clean(er) tones so I can play them at a higher volume.

Also, out of all the lower budget OD pedals, which would you recommend? I'm thinking I should go for the Bad Monkey based on its pretty solid reputation, although there are others (Boss, Ibanez TS7 etc) that I would consider, given a good reason.

I play a lot of styles, all of them badly, but pretty much all types of music have been murdered at my hands apart from metal/shred type things. I've got more influences/favourite bands than I care to mention, but I am currently in a Rolling Stones, Dr Feelgood, AC/DC and Elvis Costello phase, among many others. It's worth mentioning I play a '57 RI Les Paul Junior and a Telecaster, and in the near future either a Fender Tele or an Epiphone Archtop of some description.

I've settled on getting a Holy Grail reverb as there is really no competition in my budget (is there?) for it, so I would like something that will complement it well.

Thanks for any help you can give me!
Yes you can use an overdrive pedal as a boost by turning the gain down. The outcome of what going to happen has alot to do with you amp though. If your running a solid state, its gonna get louder and probably not start to distort any. If you have a tube, there a good chance that the boost in signal is going to create a natural old-school overdrive. I sometime due that with my pro-co rat to overdrive my old Marshall 50w, sounds very much like AC/DC. From the sounds of your musical tastes, your looking for a little bit of crunchy grit and not a purely clean sound.

If you're looking for a cheaper overdrive pedal, I would suggest buying a nicer one used. It will do wonders for your tone. You get something much better for the money. I would suggest a Pro-Co Rat, or a Tube Screamer. The Screamer is a little more "syrupy" than the Rat. You can pick them up on ebay for like 60 or so bucks if you look around.
If you use an OD pedal but turn the gain down and the volume up, you are going to get a cleanish boost but it'll probably colour your sound slightly and a lot of the time if you do that it makes your sound a little thinner and nastier. If you put it in the FX loop it'll change your sound quite a bit but you'll get the volume boost. If you put it infront, you'll just get more gain and no volume boost.

If its an unaltered clean boost in volume your after the way to go would be a Boss GE-7 Graphic EQ put in the FX loop. You'll have loads of control over your sound that way and it would be much more versatile than an OD pedal for boosting.

You can pick up a GE-7 second hand but like new for about £40 but there well worth it.
If you want a CLEAN boost, i.e straight up level boost, then no.

The bad monkey WILL color your tone and add a little gain even at its lowest gain level. That's the nature of overdrives.

Dedicated clean boosts will however just boost the signal which may in turn result in some distortion, but from the amp as opposed to the pedal.

I use mine as a slightly dirty boost. Gain on 3/10, bass and treble on 6, level on 6.5.
That's fine, I just want to get a bit more oomph at lower volumes, even if the signal does start to break up. I may look at a different pedal as suggested, but if I'm going budget then I think the bad monkey will suit me fine.
First thing I would try is bump your EQ up (low mids and treble) from the position you like it to 1 notch higher. It gets quite a bit louder when you do this. For playing clean I usually have the volume higher than needed but I constantly play with the guitar volume knob, helps when you go from playing chords which are pretty loud to a lead passage which is single string stuff that is quieter.

As for an OD as a clean boost. If you are like finding yourself needing a 10dB and you have the output cranked on the OD, gain really low, and the guitar volume cranked...you're going to get some distortion. If you roll back on the guitar volume to about 5-8 or so it will clean up and no distortion present.
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I'm in Aberfeldy! Thanks anyway. If I get one I can always return it if I'm not happy with it sure?
Aye should be possible. It's a cheap pedal anyway, I'm sure you can find a use for it. Great wee box.