Phono stage matching - how critical

The more critical matching is the phono stage to the preamp / line stage. If the phono stage is a tube unit with higher output impedance and the preamp / line stage is a low input impedance solid state unit. the mismatch will negatively impact the phono stage performance.

Dear Bpoletti, What you write is true in principle but is hardly ever a problem in practice. Nearly any worthy SS linestage will offer at least 10K ohm input impedance, and nearly any tube phono stage will offer an output Z of less than 2K ohms. Usually it's more like 1K out into 20K to 50K.

Wrm57, I am way into vintage MM/MI cartridges: Stanton 980LZS (which is actually low output), Grace Ruby, Acutex LPM320, Grado TLZ are among my favorites. I do also like low output MCs. As a group, HOMCs rank 3rd with me, which means I no longer ever use one.

Lewm - Minimum should be 1:100 ratio between the two. It is supported by more than one manufacturer.

Thanks for everyone's input.

I think it's very critical. Two points to keep in mind...the cartridge has to like what it "sees" at the phono stage input, and the phono stage output has to be compatible with the line stage input.

The first point is most critical, input impedance and capacitance isn't for the phono stage's benefit, it's for the benefit of the cartridge. This is so for MM, MI and MC cartridges. Wrong setting and the cartridge may seem to "ring" because there's a peak in it's response. In other words, the frequency response is not flat because the cartridge is also acting like an inductor.

MM and MI cartridges for example like to see 47,000 ohm at the phono stage input, MC's like to see much, much less. Therefore, using a LOMI cartridge on a phono stage set for MC gain and typical MC load and capacitance will not sound the same as if that LOMI cartridge was used with a higher gain MM phono stage.

It is for this reason that I believe no single phono stage fits all situations. "My phono stage sounds great on my system, but not so good on a friend's" sort of thing, and vice versa.
I spent yesterday afternoon auditioning four different phono stages on a friend's system. The results on his system were very different than the results on my system. The only major differences between our systems were the cartridges (MC vs MI with similar output) and amount of line stage gain. Fine tuning the loading and capacitance on each system was necessary to attain the best sound for each situation.
They all work, one way or another. But if you want to get the most out of your vinyl, it seems proper matching and fine tuning is necessary. If the cartridge doesn't like what it sees, the sound may be splashy or boomy.