I wold not change much on actual your setup but maybe dsp. So if you want to spend money, get a minidsp flex with dirac, even on those old systems that can have a very good impact. I did program a minidsp HD (not even the actual good ones) as active crossover for a Altec/JBL hybrid system (Altec 288-8K tweeter in JBL 2366A horn (with adapter) and Altec 416-8B in a custom Onken cabinet designed for it) and that did bring that system more close to the 21st century without loosing the altec sound.
You could also replace the tube amps by solid state, but then i would go for lower power class D, like one of the many itterations of the Hypex Ncore NC122MP module (i use the one of Audiophonics) that gives 75w in 8R. But then you will loose the typical tube amp sound (high harmonic distortion, low damping factor) which may not what you want. The Aiyima 07 is a good basic amp, but need the right psu to do that (and that seems to be complicated). The Audiophonics and other itterations of the Hypex Ncore MP series is all in one, plug and play, and the lower power ones are not that expensive. And they are also among the cleanest amps arround, even the older NCore (without x) versions. Altec is not made for high power amps, even the 416-8B woofer only can handle 50w i thought (but is very sensitive).
But again, the biggest impact will be adding a dsp crossover to such system, then you can make it sound like you want (within some limitations of the drivers off course).
As for streamers, i don't stream much, but i think a good computer with a good dac is as good as the best streamers arround, and more flexible in use and upgrade. Then you need music software, but many, some free (Foobar), some paying (JRiver, Roon, Audio Nirvana) are arround and are often more usefull than the limited software possibilities of a streaming device. And if you only use streaming services (no local files), even the app of streaming devices is enough as music software and often also remote controllable by your phone. You more need to look at the convenience here, as the tech is relative mature and on sound there are little to no differences (ignoring dsp possibilities of some) between the different streaming devices (dedicated or computer based). The difference in sound is the dac, but any modern dac is at least decent enough to be almost transparent...
So to be more specific on what you can do to upgrade the system:
- Replace the analog crossover with a good dsp (MiniDSP flex with dirac) and a measurement microphone (Minidsp UMIK-1) and
REW software (freeware) to finetune the speaker.
- Get modern amplifiers, but relative low power devices with 4 channels in total, like 2 x the Audiophonics MPA-S125NC stereo amp (in Europe) or the Buckeye Hypex NC252MP 4ch Amplifier (in the USA).
Get a way to stream or play digital files in high quality (including a modern dac if you don't have one yet). If you got the mindsp flex, the dac part is already done as it includes a very good dac next to the dsp part.
, even with the big KH420's or so....
