A Black Box to Solve Everything

@koestner It doesn’t solve your inquiry completely, but Modwright released his Analog Bridge about nine months ago. I was one of the beta testers for the unit. It is meant to be placed anywhere you desire, especially between preamp and amp if applicable, or just between a source and preamp. It’s not cheap, but it is very high quality and offers a good amount of flexibility in the three tube types it supports. 

https://www.modwright.com/products/analog-bridge.php

In pro audio there are any number of devices and even more software products that emulate tube distortion.  Some actually use tubes, but most use DSP to achieve their sound.  They are widely used as an effect.

A company call Line 6 has a very well received line of guitar amps that DSP model a variety of tube based guitar amps.  They might not exactly nail a specific amp, but they get pretty close and can sound quite good in their own right.

Well, allright, allright, allright. We're getting somewhere.

The quest for the holy grail in guitar amps (SS amps that mimic tube amps) has been going on at least since the 70's when companies such as Gibson, Peavy and Yamaha offered such products. You can now buy a tube Fender Deluxe Reverb or its lighter, more affordable, SS counterpart. There are also numerous guitar effects pedals that aim to do the same. Kemper seems to be very popular with pro guitarists, currently. 

Tubes for guitar and tubes for hi fi have very different objectives. Audible distortion for a guitar amp is a desirable feature, not so for a hi fi amp. Two different worlds for the same technology.

Adding anything in the path of tube gear for hi fi runs the risk of masking the transparency that many hi fi tube lovers crave. It’s not uncommon to hear of SS hi fi amps that emulate the tonal balance of a tube amp (aka "tubey"), but they don’t necessarily have the same level of transparency that a good tube amp has.

Does your black box idea pertain to guitar, hi fi, or both?