I have a Art MPA Gold upgraded with mullard tubes that I really like.  Works great as a DI and as my vocal pre.  Unfortunately, it appears one of the channels died, and this is just the excuse I need to get a new vocal preamp to add to the studio.  I have about $500 bucks to spend.
 
I am open to just about any suggestions in that price range.  Two of the main contenders are more in the 600-700 range (the Grace 101 and the P-solo).  Anyone have any experience with either of those?

 I'm getting a lot of use out of my Joe Meek Three Q. I really like the compressor on Vocals.
http://www.sweetwater.com/store/detail/threeQ
 

 
 
My next pre amp will be this 
 
http://www.sweetwater.com/store/detail/TB12
 

 
 

whoa.  that tone beast looks pretty nice.  hmmmm.  

it will take you out of your current range..
 
but a A Designs P-1...
 
500 series...
 
and a dual rack-mount harness........
 
would allow you to expand your 500 series repertoire as you see fit,
possibly with another EQ section,
or even a compressor.
 
just an idea.
 

http://www.adesignsaudio..m/500-series-mic-pre.htm

http://www.sweetwater.com...kIrm3cQCFdCTfgod6WYAIA

sven450
I have a Art MPA Gold upgraded with mullard tubes that I really like.  Works great as a DI and as my vocal pre.  Unfortunately, it appears one of the channels died, and this is just the excuse I need to get a new vocal preamp to add to the studio.  I have about $500 bucks to spend.
 
I am open to just about any suggestions in that price range.  Two of the main contenders are more in the 600-700 range (the Grace 101 and the P-solo).  Anyone have any experience with either of those?

I have been using an ART TPS II for many years and it is similar to the MPA Gold, but not with upgraded tubes.  I have used it as my main vocal pre for several years.  
 
I also have a P-solo that I've had for a couple of years.  It is NOT my vocal pre, but I use it for acoustic or for any electric or bass.
 
if you are replacing the ART MPA with a P-solo or Grace M101 then you will probably be disappointed with the results, especially on vocals, but as a DI also.  the True Systems and Grace pres are solid state only, no tubes and absolutely NO "warmth" (tube distortion) - they are very much "straight wire with gain" type pres.  very very clean. 
 
I love the P-solo for its purpose, but I don't use it when I want to hear some tube because it doesn't have any, it's just clean gain.
 
my ART TPS is also starting to cause me problems, so I decided to replace it.  what I decided on was an ART MPA PRO II and an ART VLA PRO II.  this way I replace both channels with the newer technology units of preamps and compressors.  (I also get mid/side capabilities with the MPA II which I didn't have before!).
 
the new MPA II has a higher plate voltage selector you can use which puts more voltage on the tube, giving the tube the ability to hand out higher volumes of harmonics (i.e.: more "warmth" ).
 
so if you want to replace your MPA with "clean gain" then the Grace or True Systems are the only way to go in that price range.  but if you want to replace it with something which can give you that tube sound, then you should consider the MPA II.

BTW - the Joe Meek which Johnny (Cactus Music) recommended is also a clean preamp but it also has an optical compressor and EQ, that's a lot for the money.  I've never used one myself, tho, so I can't give you a comparison on it.
 
the Beast, however, has a transformer output and you can dial in how much of the transformer output you use.  this will also give you some "warmth" - this is NOT a clean preamp.  however, the warmth of a transformer based preamp is very different from the warmth of a tube based preamp, so it will also be very different sounding from your MPA.
 
that A-Designs which Batsbrew recommended is also a transformer based pre.
 
I've not used either of the A-Designs nor the Beast, but I have used a Golden Audio and a true Neve (the GA unit is a Neve clone) and while they are not clean, they also don't sound like any of the tube pres.

The Warm Audio stuff is all very nice.  The WA12 is API-ish and has more of a vintage vibe.   The Tone Beast has a wealth of colors since it has two transformers (or none) and a choice of op-amps, as well as gain and output, which means you can drive it hard.
 
The ISA One is nice, but cleaner, more modern sounding.  It has a transformer, too, and a preamp as well as DI you can use simultaneously.  Kinda like an RND (Rupert Neve Designs), since the Focusrite is based on a Neve design.  A new RND just sounds big, or mine does anyway.  But it is the one in the Portico II channel strip, which runs on big rails w/ a lot of power.  Maybe the single space units don't sound as big.
 
I just feel having a nice transformer-based preamp works well since most of the interface preamps don't have one.
 
@

Lots of good info here.  I guess I really want the best of both worlds.  I would love to have the option to "warm it up" with some tubi-ness, but having the option of a nice clean pre would be great as well.  Seems like the ISA One might be a good middle ground of some character but not overdone.  The Beast also seem promising, as it looks like you can dial in a variety of gain structures. Too many options!!  Not to mention the 500 series stuff I hadn't even considered yet.
 
Considering that I will have just one preamp (at least for the forseeable future) I am leaning towards the Focusrite.  Its seems solid, from all accounts is great sounding, and does add a wee bit of the character I may be looking for.