Dumb question......why do you need a preamp?

I think Luxman has a good volume attenuator if that is the issue

Separate preamps and power amps provide greater flexibility to customize SQ by mixing and matching brands and models at the additional expense of interconnects, power cords, racking area, and vibration isolation.  Some will say separate chassis provide better SQ because of better power regulation due to separate supplies and better isolation from interference.  However, I have found modern integrated amps produce near equivalent or better SQ than some separates at the same price point.  I went from separates to an integrated system.  I do believe a seperate DAC and server/streamer sounds better than most fully integrated systems and here, the additional flexibility is worth it.  I also find that running a DAC with preamp capabilities through an integrated amp or preamp sounds better than using the DAC as the preamp direct to a power amp. but it seems counterintuitive.  The shortest signal path should produce the best SQ.  I cannoli explain why other than my preamps or integrated amp is of better quality than the DAC preamp function. 

at a certain budget - say X, your best bet is to get the best integrated for X. When your budget is 2X, you will get a better sound by buying a preamp and a power amp. And then, as technology changes, tomorrow some company may come up with an integrated for 2X that sounds better than the separates. It's a never ending cycle...

A good>better pre is necessary if running source to PA IF the PA doesn't have level controls onboard.  Adding switching between source and PA allows for nearly anything one could desire inline between...
....which is how I've been able to be 'pre-less' ( No, not peerless, which is another issue for another day...) for quite awhile now.  A 6x6 matrix unit allows to 'daisy-chain' as desired with whatever makes the  boats float around here...
Generally and octave+parametric room correcting eq handles dB dosage daily.

'Upstream' of the matrix is the digital 'source' switching, with 8 in/out with 3 monitor loops to select (one 'main' with 2 additional) and a diy TT 3 in with a RIAA in/out control if 'upstream' from a 'Real pre' with a 'TT in' pair onboard (getting rarer of late...but I've not shopped integrateds or receivers lately either).

Yes, there is a lot of ic's involved.....'decent', but if I went sorta SOTA it'd co$t more than all else involved and would be kinda like pig lipstick. *L*
It's more set up for the arcane audio acts I'm up to and pleases these ears.

...and it's likely what one would want if one is diy'ng speakers....sans enclosures.

I'm 'into' a enclosure-less variant in one pursuit.....

Yes, you'll have to ask wtf that means.... ;)...

+1 for the comment by Soix on the tube preamp plus solid state power amp; when I switched from all solid state, then to all tube, and then to tube preamp with solid state monobloc power amps, I achieved a significantly higher level of sound quality.  I think I have hit near end state for the amount I have spent on my system that has both digital and analog sources.  Even my non-audiophile wife—who loves good music—commented on the realism … achieved with the tube/solid state combination.