what exactly is ht bypass

actually, maybe this is a better way to understand it.
You set up your AV system like normal - running interconnects out to your amps from the "pre-out's". Now, instead of running the interconnects - like normal - directly to your amp's for the left and right channel, however, you re-route them to the "HT bypass input of your 2 channel preamp. Then, like you would normally for your 2 channel setup, you run interconnects to your amp for the L/R stereo speakers.
Basically, you're simply wiring the 2 channel system into the signal path of the pre-out's from the AV preamp, for the left and right channel. Or, you're looping the AV pre into the 2 channel - however you prefer to think about it Infact, the signal from your l/r channel out's from your AV pre/pro are simply being looped through the 2 channel preamp - and the "HT bypass" is switched on when you want to use the AV pre/pro.
Now when you want to use the 2 channel setup (2 channel preamp) for music, cd, tape, tuner, record player, whatever 2 channel sources you have, you simply run your 2 channel setup like normal, switching the 2 channel preamp to those inputs (which you have those sources connected to the corresponding inputs.), NOT the "Bypass" setting! And correspondingly, you only need to turn the AV preamp on when you are using that for movies, er whatever else is connected to that pre/pro.
Good luck

"HT Bypass" = bypassing your home theater! - lol

No, actually, the bypass means bypassing your preamp functions for those channels that are output for HT dubties!
What happens is that your volume, tone controls, etc are bypassed in that input when you select it! Any signal being sent to that input goes directly through to your ampilfier, without any pre-amplification from pre/pro. Basically, you run your L/R main speaker outputs from your AV pre/pro or receiver to that input, when you want to add a multi-channel HT system, looping through your 2 channel pre. It's rather simple really.
It allows you to keep your 2 channel system setup as normal. And when you want to run your multi-channel ht processor, you can simply use the 2 channel amp setup you are already using for your L/R channels, without having to disconnect the 2 channel setup - because you still need the l/R channels from your 5 or 7 channel av processor, and your just simply using the mains and amp set up you have going to 2 channel pre and dubties, for your main l/r's of your theater! It's just a convenience feature, that's all.
If your 2 channel preamp didn't have this (actually Auxilary does the same, as would "tape-in"), you would likely have to disconnect the 2 channel preamp from your 2 channel amp, and reconnect it to your AV pre/pro when you payed movies - which is assuming you still are trying to use your stereo speakers as part of the HT system.

thanx for the input guys...i am clear now..i may post again when the pre arrives...till then..cheers and happy listening

Yes, If you can switch between those two inputs...or the sub will do the switching for you.

Just make sure that the manual states that you can use both inputs at the same time...and not, one or the other.

Dave

i dont know if this clears up the sub issue..but..i just re read the manual..it has the option for 2 inputs specifically for this scenario..it can be run into the l/r input for pre..and the lfe for surround...dont know if all subs have that..but it was a nice surprise...will that solve the sub problem

The subwoofer can be a problem, although there a several work around solutions.

The sub needs to stay at the reciever to remain active at it's present level.

You could move it to the new tube preamp...this does involve some amount of trade off...loss of (LFE's).

I would go into detail regarding any advantage/dis-advantage....but I'm not yet clear on your goals, and don't want to confuse you with info overload.

In my system...which is setup for several playback options (audiophile, and non-audiophile), I do the easy way out....run more than one sub.

Dave

thanx guys....this seems to be one of those things i really cant wrap my head round for some reason..odd as i have dismanteld..and 'remantled'..lol..my system a hundred times..let me tell u my system..perhaps that will give u guys a better idea here..currently i have a yamaha receiver..connected to a dreadnaught amp..3 channel....so..i have the outs from yammy going to L R C on theta..and surrounds and sub powered by yammy. I want to add a pre tube because i love listening to music. So..the pre has 2 outputs and an 'ht bypass'....one output would be for mains..one for sub...so..if i go mains then from yammy to ht input..then to dead?..center can still go from yammy to dread...ahh..i see..sub wont be powered by yammy..therefore..will not mesh into ht?..am i getting warmer on all this!!..lol..thanx for the anticipated help

I am looking at doing the same as soon as the money is there. My sights are set on the LS26. One thing I have learned while deciding what to buy is that some manufactures refer to this feature as "unity gain" so keep that in mind when shopping. As Mrjstark stated it allows you to use one amp and speakers for both 2 channel and HT and basically the HT Mode on the stereo pre amp is just a completed circuit between the pre-pro and the amp and when in a source input is selected the pre/pro is completely out of the picture. I just learned about this last year from a factory rep at the RMAF and realized I can have a 2 channel and a ht system on a budget I can afford....eventually.

It is not difficult. All you need is the right preamp.
And I would suggest getting the tube preamp with HT pass thru rather then using your processor. The only preamps (tube) that I owned that had this feature were Dodd Audio and Granite Audio. It is as simple as ABC. In Dodd's case the unite did not even had to be turned on for this feature to work...as long as you turn its input selector to HT bypass input. Very cool, and saves tube live.

With "Home Theater bypass" inputs , you can plug the left and right front speaker feeds from your surround processor into the preamplifier's HT bypass "in". Using your remote control or manually, simply press 'HT bypass' or turn the input selector knob and the preamp goes into its fixed amplifier mode enabling your surround processor to control the volume.

More likely the way to run it is with sub, center and surrounds from HT pro..this is because of crossover, leval and delay sttings a tube pre wont offer. A HT bypaas is pretty much what it says as it simply will bypass its own volume, balance and even mute to allow total control of system from the surround unit's outgoing signal. I run a non HT bypass tube pre and its easy to do as you just need to know master volume of tube pre so Processor has correct levels all around but I dont use a sub for 2 channel, and thats you major roadblock.....unless you can input 2 signals into sub via multiple jacks on its inputs or via splitters from your pre and pro without any issue its gonna be a hassle.