crisis,
It depends on the amp. That's why Mesa's effects loops have adjustable send controls so you can set it accordingly.
timokeranen,
Your compressor and preamp are fine, but take the delay pedal out from in front and put it in the loop where it belongs. You don't put delays or modulation effects in front of your amp's preamp or they'll generate noisy artifacts and decay noisily and unnaturally. Having a muddy tone in the loop unfortunately doesn't automatically make it fine to run the delay in front of the amp.
As to that muddy tone, you must understand that the point of making that pedal was to recapture the more natural decay tone of earlier, bucket-brigade circuit analog delays. You see, in real life, higher frequencies roll off much faster than bass ones do. Therefore, with each repeat, the tone will be darker and darker.
Now, if the very first repeats are still too dark, you may wish to check any of three things.
1) Check the gain level on the amp. If it's too high, it will compress treble frequencies and limit-boost muddier bass frequencies in the effects loop signal.
2) Check the send level on the effects loop. If it's too high, it will do the same thing as described in 1) above.
3) Check the tone stack of the amp. If your bass knob is too high, well...that's a bit self-explanatory. If your mids are scooped, you'll have the same problem. If your treble is too low, same deal. It might even be that your presence control is too low, though on Mesa's, that's rarely a problem.