HELP! Need Reverb but got no loop!!!

[chooseyourblues]

Hi everyone. I have a Blackstar Artisan combo amp which is the best sounding amp I have ever owned. I will not sell it.
It does not however have an effects loop as it's based on a vintage Marshall / Vox.
I would desire a little reverb as the amp has none but every pedal I try in front of the amp sounds bad.
As soon as I get the reverb leval right on a cleanish sound as soon as I up the gain the reverb goes crazy and sounds like I'm in a cave.
All i want is a little 'verb for a touch of wetness - nothing crazy.
I have tried a Digitech, Boss RV 5 a Marshall (it broke) and a Holy Grail and they all sound thin and brittle.
Anyone any ideas on what pedal? I guess some will work better in front of an amp than others and some will have to work in the loop.

[Van Noord]

Have you thought about maybe trying an Echo pedal? They can yield similar results as a reverb pedal and can be set minimally to achieve a subtle effect.
I have a very inexpensive Danelectro FAB echo that works well in front of my practice amp. They are $15-$20 and worth at least looking into.