effects loooooooop

[adadglgmut]

alright.

so i picked up 2 new pedals, an EHX stereo mem man and a Diamond Halo chorus.

I ran them through the effects loop on a really old marshall valve state combo, and they completely changed my tone! Even on stand by! kind of a thinner, mid humpy sound.

Now, when i moved them out in front of my amp, they worked fine, although the looper in the EHX seemed to have a tough time playing back the loop and new playing at the same time (maybe too much input to the amp itself??)

Anyways, my question is this:

Can i expect the same thing out of my Engl Invader? Im not too bummed about the marshall because its just a practice amp. Is it possible that the effects loop in it is just old and facked?