#1
At the moment I use a Marshall DSL401 hooked up to a Marshall 1960A for gigs. The Marshall is probably the core tone I need but this amp needs a lot of work to get it where I need it to be. I use an overdrive to tighten up the amps own distortions and a Hardwire Metal Distortion pedal for higher gain tones. It's workable but not ideal. I like having the 1X12 format as I can use it for practice at home and then easily hook it up to the cabinet for gigs. My band is basically Rock covers and plays a wide range of material from the Doobie Brothers to Black Sabbath levels of gain and even higher. Where gain is required I will normally use more gain than on the original song but there are also certainly songs in the set where I need a good clean sound. So, if I were to upgrade my sound, what should I do?

One option is to sell the Marshall and get a different amp. I don't mind going used and have considered something by Peavey, Blackstar and Egnater as possible. I think these are all good amps but the tonal options may be more limited and is the more expensive route. The other option, due to the range in tones I need, is to keep the amp but sell all the pedals and get an RP1000 so I can use the Marshall as my core tone with a range of effects but use the amp modelling into the effects return when I want a different sound. This may not give me the absolute tone of a good amp but will offer far more options and is going to be considerably cheaper. I'd guess that if I had to I could maybe go up to the £500-700 bracket but I'm in no hurry to spend that much money. If I can do it for less I'd rather do that.
Gibson Les Paul Studio with Catswhiskers pickups
PRS SE 'Floyd' Custom 24 with Creamery pickups
Fender Standard Stratocaster with DiMarzio pickups
Takamine GN30
BluGuitar AMP1
#2
With 700 quid, you can get nice and versatile amp heads already. I'd look into that and maybe a 1x12" cab later if you need it.

700 will get you a used Engl Blackmore, which does a lot of genres convincingly. They can be bought for around 700€ on ebay.de (a bit rare on ebay.co.uk), which is roughly 600 quid. Add a little for shipping and that's it. There's one there right now:

http://cgi.ebay.de/ENGL-Blackmore-Signature-100-TOP-/330438631861?cmd=ViewItem&pt=Amps&hash=item4cefad61b5#ht_500wt_1154

You'd have to ask the guy if he ships to the UK first though.


There's more of course. Framus CS tops are nice if you like a more vintage-y tone. H&K, Orange, Marshall, Laney and others make nice stuff that can be picked up used in your price range... but I'd ask you to be more specific about the tones that you want before recommending any other stuff. Which are the most important?
#3
For clean tones I play 'Long Train Running', 'Higher and Higher' and 'Will You Still Love Me Tomorrow'. At the other end of the spectrum I play 'Paranoid', 'Children of the Sea' and 'Neon Knights'. In between it's stuff like Free, Bad Company, Iron Maiden, UFO, Nazereth, Thin Lizzy etc. As a result, the basic Marshall tone suits me very well as it does all that stuff in the middle perfectly but it does struggle more on the extremes and without the overdrive pedal I find the standard distortions on the amp too mushy. I like a distortion that is warm, organic and has plenty articulation. For the Maiden and UFO type songs, imagine me using gain levels that are somewhere between the originals and high gain. When I play the Sabbath songs I move more into Sabbath, BFMV and A7X sort of territory.

You're right that there are options available as amps but I don't want to spend that sort of money if I don't have to. It was because I need an amp to do so much that I started thinking of the RP1000. I've heard bands using multi fx units before and they sound fine and seem to cut through the mix OK too. Theoretically they're a good solution but I'm nervous in case I regret it later. I used to own a GNX3000 and it was good through the effects return of my amp but tone was compromised to a degree for that versatility. I'm guessing the RP1000 has moved on from there so may be somewhat better.
Gibson Les Paul Studio with Catswhiskers pickups
PRS SE 'Floyd' Custom 24 with Creamery pickups
Fender Standard Stratocaster with DiMarzio pickups
Takamine GN30
BluGuitar AMP1