RS was an interesting place for audio back in the 70s. What was fun about them was that they'd source audio components seemingly without considering the quality, but for the price point they wanted to reach. So the quality in a particular receiver, say, might be fantastic or just crap. But there were some real corkers: I found a Sherwood-made receiver with MOSFET output stage, one of the very first with digital tuning, with amazing, warm 60 *real* watts of power that they sold in '79. And there are various speaker systems that are still looked for by the vintage audio crowd, to just name a few examples.
As for components, in addition to restocking the components themselves they need to hire staff who are enthusiastic about DIY as well, so when you go to ask if they have a particular type of relay in stock you don't get the deer-in-the-headlights, thousand yard stare.