IF, existing system, you have a TT, and some kind of Phono EQ in your Preamp
1. find a better sounding Phono Stage. Buy with return privileges’, it may take a few until you find one you really like. i.e. making your existing cartridge sound better.
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2. NOW, knowing the Phono Stage is a keeper, it’s time for a better cartridge.
You will hear the most change via the cartridge, now through a phono stage you know is doing a great job. That’s why Phono Stage 1st.
a. MM Moving Magnet. There is the issue of ’wonderful sounding’, which is subjective, read reviews, research, ask specific advice.
b. There is the issue of IMAGING. That is revealed in the cartridges specifications, two of them very relevant to IMAGING.
b1. Wide Channel Separation
b2. Tight Channel Balance. Importantly to refine what is within that wide separation.
b3. My recommended MM Cartridge (to start or move up from a basic one):
https://www.audio-technica.com/en-us/cartridges/type/moving-magnet/vm540ml-h
channel separation :28db; channel balance: 1.0 db; microlinear stylus tip.
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A great LP helps you hear the Imaging Differences.
https://en.wikipedia.org/wiki/Friday_Night_in_San_Francisco
the last two tracks on side two: all 3 guitarists play.
a. get it in CD, so no imaging error is involved
b. get it in LP. IF your cartridge is properly aligned, it should sound/image the same, if not, then something is wrong with cartridge setup, fix it.
c. now, TT sounding like CD, listen to the Imaging, wide? tight? hear center/left/right guitars more distinctly?
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3. Move UP to the advanced technology of MC Moving Coil Cartridge (MC: lightweight coil inside a magnet rather than a MM: heavy magnet within a coil). Same thing, reviews, recommendations, ask for specific advice, research, don’t forget Channel Separation and Balance for imaging.
MC low signal strength (some are MC High Output signal strength) takes more advantage of MC technology’s. That low signal needs to be ’pre-boosted’ up to typical MM cartridge strength, then Phono Equalized like any phono signal.
Either the Phono Stage you bought has MC capability, OR, like me, you use a SUT Step Up Transformer to boost the MC low signal strength UP to MM signal strength.
My recommended MC Cartridge: (to start or move up from a basic one):
https://www.audio-technica.com/en-us/cartridges/type/moving-coil/at33ptg-2
Channel Separation: 30db; tight channel balance 0.5db; similar Microlinear Stylus Tip, now on a stiffer Boron cantilever.
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4. Now: a better TT, and a better tonearm.
I recommend a tonearm with a removable headshell, so you can easily change cartridges, yours or hear a friends cartridge thru your system, and perhaps a MONO cartridge IF you get into Jazz, hearing the developing years of many Jazz greats, which typically leads you back to Mono LPs (stereo came out in 1958).
CAREFUL selection of used may get you ’more’ than new TTs in your budget.
I prefer DDQL, Direct Drive Quartz Locked Speed, Heavy Platter, Heavy Base, successful Isolation.