Im going to disagree a bit with your Maggie dealer, although technically speaking he may have a point. I highly doubt running the preamp outs from your Marantz to a high quality stereo preamp is going to degrade the sound meaningfully if at all, especially since this will be in HT mode where purity of the signal is relatively less critical. Plus, the lion’s share of any signal degradation is coming from the preamp section of a $1000 audio/video receiver, not a good stereo pre. Suffice it to say, from my perspective the flexibility and increase in the number of options open to you for a good stereo pre without HT bypass far outweigh any signal degradation you’re likely to experience in HT operation. And more options also means you’re more likely to get a better deal. All else being equal I’d prefer having an HT bypass for the convenience of it more than anything else, but in audio all else never seems to be equal.
BTW, there is a nice McCormack DNA1 amp with Steve’s silver level mods available here now for about $1300 that should drive your Maggies nicely and sound great. Might be worth a look along with Bryston. I'd look at the SSTsquared Brystons as I found them to be more refined sounding than the original SST. A tubed pre with a solid state amp can be a great combo (I'm going this direction myself), but keep in mind in most instances you'll be burning through your tubes while watching TV since you'll likely need to have your stereo preamp turned on in this configuration.
Anyway, that’s my $0.02. Hope it helps and best of luck.
BTW, there is a nice McCormack DNA1 amp with Steve’s silver level mods available here now for about $1300 that should drive your Maggies nicely and sound great. Might be worth a look along with Bryston. I'd look at the SSTsquared Brystons as I found them to be more refined sounding than the original SST. A tubed pre with a solid state amp can be a great combo (I'm going this direction myself), but keep in mind in most instances you'll be burning through your tubes while watching TV since you'll likely need to have your stereo preamp turned on in this configuration.
Anyway, that’s my $0.02. Hope it helps and best of luck.