Trevor, great question to which the answer, is slightly different to the question you posed.
There is a good classical thread, but I think best to listen than trying to take in all the posts.
First if you are interested in buying s/h vinyl, you are best to either have access to, or own, a RCM.
Second, consider adding a streamer to your system (unless you wish to add a tuner). Great source is streamed radio or one of the streaming services.
In the case of radio, you need look no further than radio 3 from the beeb. Proms playing every night until September and on demand for a further month.
Listen each evening - ignore or switch off if it is not your “scene”. @Ian2001 has highlighted one programme, I will add two more, the R3 breakfast show at 6.30am and in-tune 5-7.30pm.
Listen in the background when something catches your attention, you can ascertain what you enjoyed, by looking at the play list on the beeb programme website. (Unfortunately ascertaining the same on Naim or Linn classical feeds is not so easy).
Once you have an idea as to what appeals, the sub category genres are numerous, then it will inform your perusing in the dedicated sections or shops that you can visit.
The s/h shops are now wise as to the value of these pre-owned items, in part due to discogs. DG long ago were reliable recordings, but so were many others. HvonK was popular and usually good quality, but there are other interpretations - a personal choice. My collection has seen too many decades for my liking, but they are all in good condition. Happy listening and hunting - yes there is something more rewarding than a stream feed, if you hold a record sleeve. The plastic incarnation of a music source is best forgotten in a tactile context!
edit - for those of a classical leaning - R3 Sean (or was it Petroc?) last week, mentioned that one of the independent classical labels in the uk, are set to start to stream their back catalogue; - apologies for being a bit vague - I need to check, I only caught the comment in passing.
edit 2 - This from the classical-music website British classical label “Hyperion Records has today made part of its catalogue available on streaming platforms. For the first time in the label’s 43-year history, 200 albums will be available for streaming from today.” It is to be an ongoing project IIUC.