Several questions. I currently only have a 2-channel stereo setup with the RR 2150. I'm really not interested in HT. However, if I later want to add surround, I assume I can use the external loop input to receive the front LR channels from a surround processor/receiver? The manual states that it can, and I assume this is one function for this feature. Is this the same or similar as the HT passthrough feature you see on other receivers?

The primary intent of the external loop is to support devices such as equalizers, which is different from a "home theater pass-through." I'm not sure how Outlaw envisioned integrating a surround processor with this, but you could run the pre-amp outputs of a surround receiver into the external loop input and thus have access to that signal simply by engaging the external loop. I would see one challenge there, though: the 2150's volume control will be applied downstream of the external loop input, so you'll have two volume controls in series.

Here's another option for integrating the 2150 with a home theater setup: remove the jumpers between Pre-Out and Main In on the 2150, set up a switch box, connect the pre-outs of both the 2150 and the surround receiver/processor to the switch inputs, and connect the switch output to the 2150's main in. In that way, the 2150's volume control would only work when the 2150 was being used as the source, and the 2150 would serve simply as an amplifier for the home theater setup. A reasonably good switch should be sonically transparent.

Thanks, gonk. I appreciate the information.

The external loop would also be ideal for inserting a tube buffer. Just a thought.

That's strange that the volume control would be controlling the processor loop.

The only reason I say this is because I've had a couple of 2-channel stereo preamps over the last few years, and my current one, an Adcom GFP-750, has an ext. processor loop, in which the volume control is bypassed, and my 5.1 processor with center and rear amps(a Yamaha DSPE-492)'s front pre-outputs go straight through it, to the 2 channel power amp, letting me use the surround proc. for overall volume control.

Maybe the Outlaw unit and designers have a reason for what Gonk was describing.

With other 2-channel units I had to use a tape monitor loop, and keep the master volume at half way.

The external loop itself isn't affected by the volume control, but when you come back into the 2150 you will hit the volume control. It does that because it is intended for use with external processors like EQ's. That's why the external loop isn't really the same as a "home theater bypass" (which skips the volume control entirely, allowing the stereo receiver to act as a stereo amp).

Prior to the introduction of Dolby Digital/DTS, there used to be processors with Pro-Logic and three power amps. You inserted them into the pre-main loop, so that the matrixed signal would come out of the two-channel preamp, be decoded and channel-balanced in the processor and the front channels fed back to the receiver/amp's main (the processor took over all the volume and channel-balancing control from the receiver and powered the added channels). But the original tone and volume controls would only affect two-channel matrixed sources; any digital sources going directly into the processor would not be tone-controllable, since they went directly from the processor to all the power amps. I've not seen any DD/DTS processor/amp add-ons, so maybe that was the fatal flaw of the concept.

There are a few issues that arise there. First, DD/DTS decoding has to happen in the digital domain, whereas those Pro Logic units were analog. This creates some major problems, since those digital signals simply don't work with an analog stereo receiver or pre-amp. If you add a digital section to that stereo unit, you may as well just make it do all the processing itself and avoid the second chassis. Second, Dolby Digital and DTS are now being joined by (or even pushed aside by) Dolby Digital Plus, Dolby TrueHD, and DTS-HD - all of which require HDMI for digital delivery. That just exascerbates the problem that we already had. Merging any of this digital processing downstream of a two-channel analog pre-amp is simply too costly and cumbersome.

The alternative that has arisen in some circles is stereo receivers or pre-amps with a "home theater bypass" mode of some sort. What that allows you to do is basically graft two separate systems together, creating a multichannel system that shares its left and right channels with a two-channel system. When the stereo pre-amp is in bypass mode, it accepts the left and right pre-outs from the surround processor and sends those to the amp. (In a stereo receiver, of course, the amp is internal.) When teh stereo pre-amp is not in bypass mode, it uses whatever sources are connected to it and does all of its own volume control, tone control, and so forth. I guess you could do this with the RR2150 by setting up a switch box that had two inputs (one connected to the pre-outs of a surround processor, the other connected to the pre-outs of the 2150) and one input (connected to the main-ins of the 2150). [Edit: and apparently if I'd scanned back through the whole thread, I'd have seen this same idea in a previous post that I made. At least I'm consistent, right? ]

I think the "home theater bypass" is nothing more than a switch on the front panel that saves you the trouble of fooling with re/main jumpers or building a switchbox. For receivers that previously didn't have pre/main jacks this is a bigger design change than it would be for those that did. But since you'd still lose tone control, where you end up is just at getting a whole preamp and a multi channel power amp...both of which already exist in the Outlaw line. So maybe all we really need to do is start lobbying for them to come out with silver versions of their other components.

I'd still miss my tone control knobs, though...

Yes, home theater bypass is functionally the same as a switch box in front of the stereo's "main in" connection. In that scenario, you still have your tone controls (and tone control knobs) for stereo sources played back through the stereo receiver. The logistics of digital audio are such that you're simply not going to be able to integrate surround processing downstream of the stereo receiver without bypassing the stereo receiver entirely.

I suppose they could do a surround receiver or processor with the 2150's "retro" styling (the "silver" aluminum faceplate, blue-trimmed knobs, and a minimum number of buttons), but it would be a radical departure from their existing industrial design standards. It'd almost require two alternate faceplates for the same platform to avoid losing sales based on aesthetics: one "standard Outlaw" and one "retro Outlaw" (probably at an up-charge due to small quantities and additional fabrication costs).