Cary SLI80 as just a preamp?

Another idea.  If you are attempting to now use a SLI-80 integrated amp as a preamp instead, another option would be to sell the SLI-80 and apply the funds towards a second hand SLP-98 preamp. Similar value on the used market. Having owned both, the 98 is a better preamp, has two sets of Pre-Outs, one set for your main stereo amp and a 2nd set for a 2nd amp or subwoofer(s) if you need that.  

The header logo at the top of this page also reads "A discussion forum by Audiogon".

Asking here about removing tubes from your SLI-80 to use it in a way it was not designed to be used, most would simply advise to contact the manufacturer with your serial number. There are cautions in the owners manual about removing the bottom plate, with a logical safety reason for this.

Some designs use filter caps with a sufficient voltage rating to handle no tubes plugged in, then checking B+ voltages, plates, screens. Who knows what’s installed or been changed in your amp since new. Various caps were used in SLI-80s over the years. Since you came to the Tech Talk forum looking for technical information, do you know what’s installed in your amp now? Do you know how to check values? If not, back to logical step#1.

Its a good thought experiment and it "could" work with some added investigation and validation of what is inside. And, perhaps the point earlier is it could also be a waste of a good SLI-80 amplifier to use it as a preamp only, long-term. Not saying you would do that, just noting this.

The previous "idea" I brought it up was more related to previously owning a Signature SLI-80 amp with mods, and eventually selling the SLI-80, then went to separates (like you are kinda thinking about now with a separate amp) and discovered how good the SLP-98 preamp is with similar upgrades. If you like your current amp or a future amp, and wanted to go this route, it’s also a great option as another "thought experiment", i.e. non-Tech Talk discussion :). Cary owners discuss this kinda stuff quite a bit branching from one model to the next, fyi.

I too now use completely different brand mono tube amps in combination with my Cary preamp, and pleased with the results. "Thought experiments" and discussion like this can lead to some really cool changes in ones system, fwiw.  

@ozzy62 
Since the SLI-80 is only an average (I'm being kind here) sounding integrated amp, I would have my doubts that it would make a very good preamp. 

The standard version is less than the F1 version, and a fully upgraded SLI-80 is in a completely different league. Not even close.  

After helping on three sets of custom speakers for a 50-year retired tech friend, in return he did his magic on my former SLI-80 signature. It turned out to be well beyond the old F1 version upgrade.  Caps, diodes, resistors, better quality grade wiring, more +great NOS tubes.  Cary asked to see it and hear it, so I sent it back for them to demo. They were stunned. Ended up buying it back from me for FULL price plus parts. Moved on.  The Cary SLP-98 preamp with outboard power supply, better cap option upgrades, and good tubes is even better.  I've tried it with 4-5 different amps, like it quite a bit, fwiw.