I think I can appreciate the points you make about liking '80s/'90s era audio gear, and that you like the spectrum analyser on the Technics amp.
At the same time though, you've also said that you heard a big difference with the Cambridge Audio amp compared to the Technics, and that you're working on a budget (but you haven't said what that budget is).
I'm sorry to have to point it out, but IMO there's a bit of a conflict here. Entry-level
Hi-Fi amps - even ones from the '80s and '90s - didn't/don't have spectrum analysers.
I'm in my mid 50s, so I'm old enough to remember this sort of gear when it was new. I started reading about and buying Hi-Fi gear in the early '80s. Graphic Equalisers were a thing. Spectrum Analysers would come a few years later when LED display tech improved and got cheaper. The point here though is this kind of tech' was found on late '80s stack systems, or in the Pioneer and Technics separates catalogues. Both brands made credible mid-Fi product. This was stuff that was okay, but didn't really stand out from the crowd.
There were some exceptions. Pioneer, had an excellent 50W/ch budget Hi-Fi amp in the
A-400 from 1990. Around a similar time, Technics had the 100W/ch SU-V900. Despite the extra power though (and the extra cost!), it didn't have the insight or entertainment level of the cheaper Pioneer. That is the problem here. You like what the Cambridge Audio A1 does, but you want something from a stereo equipment range that isn't built to do this.
Your choice then is to either buy the same sort of amp that you already own - even though it doesn't sound that good - or to go with an amp and a separate Spectrum Analyser. But here you hit the second problem; second-hand prices have gone very high - £150 / £250 / £400!! - for old bits of gear that 10 years ago you could have picked up for £10-£30. The price is fuelled by nostalgia rather than quality. Modern tech does a better job.
The EQ in a modern AV receiver uses a microphone to listen to the sound from each speaker in the room. It factors in the room effect, and then corrects for it. You still have tone controls, and you can override the EQ and tweak it to what you think sounds best, but in general it does a blooming good job of fixing a lot of common sound problems.
If you still want the flashing display, then instead of wasting a tone of money on some over-priced poor quality Equaliser, go buy the Fun Generation RTA-31. It's £115 + shipping. The frequency range is divided in to more segments (31 rather than the usual 7 / 12 / 15 of older gear) and it does a variety of display functions. Put the money saved into a better amp.