#1
For general information purposes, due to a prior thread posing the question of how to bypass tone controls on a combo amp -

Back in the original days of Amp Heads and Combos, the systems were simple and limited in that you could only plug into the product in one place, that was before the pre-amp.

Since the popularization of Effects Loops this has no longer been the case.

An effects loop allows the insertion of processing equipment between the Pre-Amp (Component/Stage) and the Amplifier (Component/Stage).

On some Combo Amps the speaker is not hard wired to the amp section. Often you will find a plug with the leads to the speaker plugged into a jack in the back of the amp. This is great for Trouble Shooting but also gives you the opportunity to rune that speaker with a different Amp System completely bypassing the Amplifier that it came with.

It can be as simple to use as a Female Mono to Female Mono adapter, or a Female Mono to Speakon Female Adapter.

I have done this to prove tone from new rack mounted amps similar to the combo amp.

Similarly, there is no unwritten rule that you have to use all of the component stages of a product. As long as you can get electricity out of something, or into something you can exploit the circuitry for your own purposes.

A Pre-Amp Stage can be exploited and used to:

A run a power amp or other power sections of amp head just by taking the signal out of the Effects "Send" and go to the recording console.

B. If you want to run a different amp, use an instrument cable out of the Effects "Send" and send the signal with the instrument cable.

C. If you want to rune the amp that the Pre-Amp came with and an additional amp, you can use a signal splitter (or Y connector), come out of the Effects "Send" and use a short patch cable to return one mono plug to the Amp's Return, and an Instrument cable out of the second to send the signal to the "Return" of the Effects loop of the other amp head, or into the input of a power amp.

Just as C above shows.a line level signal of an effects "Send" of one Amp can be sent to the "Return" of another to make use of only the Power Amp section and by pass the Pre-Amp section of that Amp.

Sometimes this is not always the case, as in some circuitry the EQ section is Post Effects Loop, so you would have to flatten that out or "0" that out. In other circuits it is as simple as I have presented.

As a Testimonial, I have done all of these things with my GenzBenz NeoX 400, as it sounds perfect to my tastes, even better than the GBE600 I have tried to replace it with for Gig/Road Endurance purposes.

I have used the Pre-Amps to go into a Recording Array, I have split the Pre signal to run it as well as a ShuttleMax 12.0 to give me an additional 1200 watts.

I have made use of only the Master Effects Loop "Return" on the ShuttleMax 12.0 to run 4 more Neox 12" speakers.

I have made use of the speaker alone in tone proving another amp to replace the Neox400.

There are many reasons why someone might do any of these things as opposed to just getting a different product.

The fact of the matter is that even amongst similar and exact copies of products by any one manufacturer, there are shall we say, "Ghosts in the Machine" where the particular components of one amp were better matched than another, or just make that magical inspiring tone for its owner, and it is just not found by them in any other amp. Like Me and the NeoX400. (I had to get a Second GBE 600 to get the happy sound, and strangely, that one does not even use the same 12AX7 Tube).

Thus tonight I go to the studio with the Neox400 to use the PreAmp Section, and a Yamaha PB-1 as back up if it is too noisy for the Engineer.

When you find a particular component that make 'Your Sound" do not be surprised that any replacement or repair diminishes the tone and fails to get Your Sound.

When in East Hollywood I met a past producer for the Rolling Stones who said the Guitar part at the Beginning of 'Street Fighting Man' was a mess because the Fairchild compressors could not get the attack that they heard from the micro recorder that someone had used at home when they came up with the part.

They called in an Electronic Engineer to look at what they were doing, and he looked at the recorder, took it apart and handed them a patch cord with the 1/8" recording jack from the Micro recorder, and another patch cord with the 1/8" plug from the cheap external mic that was used.

Voila! That is the inspiring magic in the opening of Street Fighting Man.

So, when you find some cheap thing that inspires you and you cannot let go of for something new, you are not antiquated, arcane, or crazy, but truly an Eccentric Tone Hound.

Such is why Class A, AB, C and D amps continue to be made. No one is better than the other, except for your purposes.
Ibanez BTB 1006 Fretless and 405 (no Barts)
456 & 455(w/Barts)
Genz Benz NeoX400 112T & NeoX 112T cab.
Digitech BP-8 (x2)
Yamaha PB-1
Boss: SYB-5, PS-2, OD-20, EQ-20, PH-3,BF-3, CE-20, DD-20
Morely A/B
#2
And, of course, we've been able to purchase separate preamps and power amps pretty much all along, though they weren't low end items. I can probably find photographs of both bass and guitar players using the old Dynaco preamp/power amp combinations (and Dynaco power amp parts were the basis for early SUNN amps). Rack mount separates were all over in the '70's and '80's. Still popular for bass players, but beginner and intermediate guitar players generally aren't aware of them.
#3
Yep.

I am often tempted to go back to my 10lb PB-1, and have 4 of them, but the reaction of people to the GENZ gear has been amazing so I stick with it and find ways to use it.

As I pointed out, sometimes it is what is inside the box that is the magic, not its name, make, or actual value.

Some, like the Poster who asked about bypassing the tone section of his amp was going down that road but had no money for a Power amp and separate speaker.

Well, here is your intermediate solution. And what is going to happen if he loves what he is doing and then gets a power amp and huge cabinet and discovers that the sum of all of the pieces he is using in rack gear does not equal his prior joy?

That is the natural risk. Bigger and more expensive is not always better for every player.
Ibanez BTB 1006 Fretless and 405 (no Barts)
456 & 455(w/Barts)
Genz Benz NeoX400 112T & NeoX 112T cab.
Digitech BP-8 (x2)
Yamaha PB-1
Boss: SYB-5, PS-2, OD-20, EQ-20, PH-3,BF-3, CE-20, DD-20
Morely A/B