I h ave actually been quite impressed with the MXR cheap one. I think it holds its own against some of the more well known boutique pedals, and I can find them for $80-$100 bucks. I may get one some time.
I saw it in a vidwo with Sans Amp, EBS Billy Sheehan, and a one Darkglass, and something else. I liked the MXR and EBS Billy Sheehan best, much to my surprise, and the people reviewing it (reverb or Thomas I think) were surprised and thought both of those were the stand out pre-amps as well.
1 - reviews can manipulate sound of them (I don’t see why either of those reviewers would do that, but it can be done)
2 - hearing is subjective to the listener, as I stated before
3 - almost most importantly, high dollars does not mean better sound, especially when you take #2 into consideration.
I know you already said the SANS AMP is not your favorite, and maybe you don’t like it. I am not hugely impressed by it, but I use it as an example, because you can get a $33 Behringer knock off, showing money doesn’t need to be great for sound to be.
I was not really trying to suggest the MXR to your list, I was merely joining the conversation, but I have come to like that little box (and in way more reviews then the one I just mentioned, also in one against 3 darkglass and the sans-amp. none sounded bad, and 4 of them sounded pretty great, and the MXR was one of the 4, I bet you can guess the other 3) and I may end up getting one used sometime to play with it myself.
And, ou can get it as the Pre-amp or Pre-amp/DI, but I have seen more with DI on the 2nd hand market, and at the same cost as the pre-amp only, so unless space is an issue, I would just get the DI and have yet another place to DI from in the chain for whatever reason, it is just added versatility I guess.