I bought 2sk170 and 2sk117 a very long time ago - more than 12 years ago . I have used them in other preamps , and I have kept a small stock from those times .
John Curl's legendary "JC-2" phono stage, used in the Mark Levinson phono preamp of the same name, was an all-discrete design. 40 years ago.
John Curl's legendary "Vendetta" phono stage, was a nearly all-discrete design. He used two opamps outside the signal path, to implement "DC servos" which nullify offset voltages. 33 years ago.
His phono stages that ship inside Parasound preamp products today, zero years ago, use all opamps. The only discretes are single-JFET current sources whose only purpose is to increase the opamps' output stage dc current.
But which is "sonically better" ? It's a matter of taste. You decide.
John Curl's legendary "Vendetta" phono stage, was a nearly all-discrete design. He used two opamps outside the signal path, to implement "DC servos" which nullify offset voltages. 33 years ago.
His phono stages that ship inside Parasound preamp products today, zero years ago, use all opamps. The only discretes are single-JFET current sources whose only purpose is to increase the opamps' output stage dc current.
But which is "sonically better" ? It's a matter of taste. You decide.
Well I'd argue that a phono preamp isn't sonically anything, since its electronic, not acoustic, but either way the question is moot since it matters which discrete circuit and which opamp you are comparing - or do you mean which approach gives the absolute ultimate best performance? In that case you have to be clear how to measure what's "best" - and different people differ a lot in this.
There are many properties of a preamp that can matter (headroom, noise, linearity, cost, EMI-susceptibility, precision of RIAA response, output impedance, single-ended/balanced output, configurability of input impedance, portability, bandwidth/roofing filtering, probably a few more I can't recall), you have to figure out the relative importance of the properties to be able to define what "better" means to you, or define a minimum requirement for the important ones perhaps.
Both approaches, discrete and opamp, can lead to very good performance, and indeed sometimes a hybrid of discrete devices and opamps can be a real winner too.