Mesa Boogie walkabout Send and Return Sockets

[jazzyvee]

I have a Mesa boogie walkabout head that I've had from new since about 2004. It's just had a repair to the send and return sockets as there was a problem with the signal breaking up. ( a common problem I've read).
 
As I also wanted to check my F1-x out after a recent mishap I plugged the full range output of the pre-amp into the return socket at the back of the walkabout.  
The sound was  fine however, whilst  expected the pre-amp controls of the walkabout to be bypassed, the master volume also was bypassed so the only way of controlling the output volume was via the pre-amp gain control.
 
My question is simply, is this correct for the walkabout?
I use this method with my pre-amp into the return socket on many of my gigs where there is a back line now because the back line amps are not usually to my liking and all of them bypass their internal pre-amp stages but always give me control of the master volume.  
 
Does mesa do things differently or does this point to a problem with the repair of the send and return sockets?
 
At the moment I don't have a device I can loop into the the send and return sockets to see if the master volume is affected in that mode too but should get a chance in a day or so hopefully.
 
Jazzyvee

[wideload]

My Peavey BAM210 is the same way. I use the F1-X to control gain - usually have to stay down around 3 or so. Made me think about going to a power amp that would let me push the pre w/o trashing my hearing, but I don't play enough anymore to want to spend the money...

[David Houck]

I just read the manual, and it's not stated in there.  However, I found one comment on talkbass that states that the master volume is indeed before the effects loop.

[xlrogue6]

Unfortunately, that's the stock configuration on the Walkabout, along with the post-only DI. Love everything else about the Walkabout, but those two things are just plain stupid. I find it easier to work around them rather than modding it, so far anyway.