Recommended setup for live performance ? - headless, set-and-forget

You have just what type of bass, exactly?

I see now from your initial topic, dated from September.  You use an acoustic!

Sometime after your first post, expressing your considering previously a real baby grand, a piano which since only became prohibitive because of the lack of available space in the venue mentioned, in addition to your budget considerations for it, Roland since released its LX700 series of digital pianos.  Certainly one of these LX700 series pianos, is cost-effective, appreciably, compared to the baby grand. 

The new series like Pianoteq, exploits modeled piano technology, opposed to lifeless digitized samples which are static.  But, unlike Pianoteq, it houses the technology inside a few finely finished variations on the aesthetically beautiful and traditional upright piano cabinetry marked exclusively by the new series.

Perhaps you are in the market to procure something eye catching; that is something especially beautiful to the most trendy restaurant goers, and, even approachable acoustic jazz enthusiasts, so long as it however is feasible to you and your contractor, or, any number of fellow business partners.

Imagine if you will, simply, piano players coming to the venue to play, irrespective of their tenures, and having purely music and music sheets or an iPad that they’ll use to eventually beautifully entertain the diners the guest who come to dine graciously!   While some players more tech savvy indeed and temperamental rightly will expect to customize LX700 parameters that are intrinsically similar to Pianoteq’s, yet differently from their tablets or phones, others less savvy are just free to raise a piano key cover and play immediately.  Without so much as a power-on button, Roland LX700 series accommodates both types of players.

Seriously, since I was a jazz drummer and maitre d’ in Northern California, let me stress you will want only piano players whom you barely know to have all of their attention fixed and focused appropriately at the keyboard you too are ultimately to adopt.  Now uprights afford a look that’s truly elegant even for modern jazz trios.  And, to some they even impart a sense of nostalgia because they’re also traditional!

The upright, a truly modern representation of the tried and true piano of the old fashioned but sorely missed eateries of yesteryear, might today permit just a fabulous up and coming singer, to perform as prima donna  —and her keyboardist, whilst engrossed by its undeniable dimensions, also engulfed in the sound of that good ole upright form, in concert. 

From highly efficient speakers built into a new Roland LX700 series digital (modelled) upright, nearby stage monitors are altogether nonessential for other instrumentalists or a vocalist to hear the piano.  They may appear all-in-all redundant.

Besides, Roland LX700 series digital pianos were designed with the absolute best in piano speaker technology, specifically marketed to meet the demand from small music venues like the one you’re planning.

Lastly from a jazz drummer to a jazz bassist, I suggest you form your jazz trios, employing the modelled pianos found in the solid digital upright series made by Roland; maybe a sort of a sometimes furniture piece, but, like Pianoteq, it relies upon modelled pianos as its basis (puns unintended).  And, make preemptive usage of Pianoteq within only your appreciably expandable MacMini interfaced by a Focusrite Clarett, since the Clarett allows you to use your favorite plugins in real-time via Thunderbolt —that is— if you should ever have somehow to compensate for any and all unforeseeable deficiencies which can present themselves in a distant mix, potentially, whenever coming out of a Bose speaker system that was once most advantageously and acoustically positioned somewhere, and somewhere always arguably temporary to a restaurateur in his own business establishment  —but understandably his however lacking structural and studio quality acoustic reinforcements and even some of the professional posh audio listening room treatments!

My suggestions reviewed are as follows:

1.)  MacMini headless computer

2.)  Focusrite Clarett audio interface

3.)  Roland LX700 series digital piano

An informative review of the Roland LX700 series digital pianos is on YouTube: https://youtu.be/6yR4pgUU2-w

I have Pianoteq 6 Stage running on a MacBook Air, connected to my FP30 (so the same as your FP90) via a USB lead. The output from the MacBook (the headphone socket) then goes to my audio system.

Even when the MacBook goes "to sleep", Pianoteq still works.

It sounds "sublime" !

Thanks all for suggestions.  Many workable alternatives to consider, apparently.

It looks like choice of hardware boils down to a few key decisions:

1) headless or not (since I plan on a set-and-forget Pianoteq use-case, I still prefer headless on stage, but will keep  screen/mouse/kbd nearby in case of trouble; will also consider VNC to iPad. Also, on-stage DP has on-board piano sounds, which could get us through a set or a night, if pianoteq box just completely craps out)

2) OS choice: Windows, Linux, MacOS (I am much more familiar with Mac and Linux. Note that I plan a dedicated Pianoteq box, running nothing else, so OS support for other applications is not a factor for me here)

3) Form Factor (I prefer smaller, but want to ensure hardware reliability under load)

4) I/O and DAC/Audio (I plan on USB for midi in, and outboard USB DAC, so 2 or more USB ports is the only key I/O requirement)

With these in mind, I see (at least) two workable alternatives seem to fit my need: Mac Mini or Intel NUC (running linux).

Looking at the dozens of models of Intel NUC, my question is CPU. Pianoteq FAQ seems to provide only general guidance about recommended cpu spec, but in these forums I see discussion about clicks and pops under heavy polyphony load, over-clocking, cores, processor speed, etc. Of course one could ensure performance by spending more on a really high-end cpu, but $$ aside, this brings cooling and power considerations into the picture.

Is there any general consensus about a minimum cpu spec above which pianoteq performance is assured stable?

I found the zotac zbox to be very reliable, like a NUC without a fan. I own a 547 (I think) but I am not using pianoteq with it.
Pianoteq is running on a i3 3120 inside an akasa euler case - also fanless. Under normal circumstances this should be enough CPU-Power. Pushing the sustain and playing with my arms - yes it probably will crackle (I could give it a try if you want to).
The point where pianoteq starts crackling depends on the OS setup, the cpu, the audio interface and also what latency you need.If you are comfortable with 512 samples buffersize it is difficult to run into problems, if you want to achieve 32 samples then your hardware requirements are high (eg RME audio interface).

Before I settled on the MacBook Airs for Pianoteq - I was gravitating towards the ASRock Desk Mini - it's about the size of a lunch/bread box; bigger than a NUC but still a decent size for schlepping to a gig. The main benefit is it supports full desktop CPUs with a proper box fan for cooling - so a lot of the performance issues from mobile CPUs can be avoided. The compatible desktop CPUs are half the price of the mobile CPUs - but still have double the performance.

Here's a video by ASRock that compares the Desk Mini with NUCs and desktops.
https://www.youtube.com/watch?v=Xg8L6iK1dDM