The discrete RIAA-equalized preamplifier project is based on the phono MM input stage of a vintage Nakamichi 630 and 410 Control Preamplifiers. Both models have nearly identical phonograph preamp circuits.
The phono input stage consists of a three-transistor common-emitter amplifier coupled to a complementary class A push-pull output stage. The design cleverly minimizes the overall noise by a factor of one-third. Such a reduction not only improves the clarity of the signal but also boosts the S/N ratio significantly, which substantially improves the preamp to achieve clearer, more precise, and higher fidelity in audio reproduction.
Listening to heavy music (hard rock genre) albums by "Creed" Greatest Hits and The Story So Far: The Best of "Def Leppard," these are difficult to listen to on an average sound system. However, I was surprised this preamp can make a significant difference to hear more clarity and depth of the music it reproduced. It is not fatiguing to the ears but something unexpectedly calming.
Furthermore, the audio quality is warmer and more real due to the analog nature of vinyl records, which preserve the original sound without compression, which digital formats do and often struggle to match. It is, in my opinion, a nostalgic listening experience that I had a long time ago.