Do I need a phono preamp?

Cartridge IS the most important.

IF your phono sounds great; IF you can hear differences between cartridges, then I would not even consider changing the phono stage until you change the preamp and/or amp.

I would consider these changes in the future:

1. Turntable with Two Tonearms, (If into Jazz: Mono ready to go, back to Stereo in seconds in a listening session). One arm easy height adjustment and changeable headshell. Other, perhaps longer arm, perhaps fixed cartridge. Consider method of choosing which Tonearm.

2. Low Output MC Cartridge, which means: new SUT to go to existing MM Phono; or New MM/MC Phono Stage with SUT built-in. Have PASS to send MM cartridge thru the SUT/Phono Stage unchanged. Consider MC SUT (internal or external) optional xFactors and optional impedances for future cartridges.

3. Tubes! Thus if new Phono Stage: Tubes, separate, or in tube preamp, or tube integrated with Phono or you go separate tube phono.

4. Speakers: to easily try tubes, high sensitivity/efficient speakers are important. Existing? New?.

Less needed power decreases cost/weight/heat; increases competition in that power category, increases placement options

Phono stages are as important as the turntable / cartridge. Over a period of ten years with a VPI Aries / Van den Hull Frog and originally a A rated (Stereophile) $200 Phonostage (which sounded simply terrible), then the 1980s Audio Research PH2, 2SE, 3…etc until I got to the ARC PH8, each increment brought very important improvements in sound. It was not until the PH8 did I feel as if the phono stage was not significantly holding back my turntable sound quality. At that point the PH8 was about the same cost as the turntable / cartridge.

I have upgraded my vinyl end now to nearly the maxed out Linn LP12 with an Audio Research Reference 3SE. The turntable/cartrige value roughly equals the phonostage. Outstanding phonostage are made by Audio Research, Presto and a couple other companies.

while I have probably heard the Mac phono, I don’t remember it well enough to comment. But typically a separate high quality phonostage makes a big improvement. Someone with more intimate knowledge will have to comment on this particular one.

McIntosh MP100 is excellent. Should work with variety of cartridges. I heard it in my system with Hana EL and Hana ML. Table was MoFi UltraDeck. 

Phono stage is most important.

Why? because the cart signal has to go through it before it hits your amp.  Imagine your ART9 going through a $500 stage compared to a $5000 stage; which one you think sounds better?  IME, a $5k stage is very different from a $500 one.

For tubes, I would find a Tavish Adagio.  Very close to the Modwright PH9.0.  The Modwright is just above your budget but it's also upgradeable should you want to go to the next level.

Solid state, the Darlington Labs MP-7, and now they have the MP-8B, is a giant killer.  My MP-7 was very close the Tavish.  I would also look at Lehman Decade or Sutherland or maybe Rothwell.

Phono stage for the win.

The entire audio chain matters, best to address the weak links. So yes, a better phono stage is a good idea since very few built-in phono stages are built to higher quality/sonics.  Lots of excellent choices.

My head hurts.. I asked myself this same question a bit over a year ago.  I purchased new a McIntosh MA12000, SL1200G with Hana cartridge and I innocently asked myself if things would be even better with a separate phono amp.  I then went down the road of trying to find a phono preamp.  I tried and returned a phono preamp in the $3k price range, but wanted to my ear a more realistic musical sound.  I can tell you right now, that is a very dangerous thing to wish for.  If you look at my profile you can see that I passed on buying a new car as I upgraded each piece of equipment.  In fact, I still have my SL1200G/Hana because it traumatizes me to look at it.  In the end, I don’t know what made the most difference, but in terms of sounding more musical, it was my phono preamp upgrade.  In retrospect, I think that I would have been better to have put all that money into the digital side of my system, but then again, I can’t bring myself to get rid of my collection of film cameras.  Just a personality defect.  Careful with the road you are about to go down and recognize that you can get more bang for your “investment” by maxing out the digital side.  A few years ago I would not have believed that digital could rival vinyl.

Thanks a million for the input everyone. I've been doing a lot of reading based on your suggestions. The Sutherland Little Loco (MK2) has my interest. It appears the connectivity issues have been simplified, and the sound quality and simplicity (no  loading requirement) are universally praised. Now if I can get Solidsteel to send me a new custom shelf from Italy, I'll be good to go. Nowhere to put it!!

Make sure that you have return privileges with the Sutherland.  Lots of glowing reviews, but that doesn’t mean that it is what you are looking for.  I tried the Sutherland - 20/20 LPS MM/MC MK2 Phono Preamplifier and found it to be very quiet, but didn’t work with my taste and equipment.  The model your considering is upscale from the one I tried and your components differ from mine.

In retrospect, I think that I would have been better to have put all that money into the digital side of my system,

Thanks, @vonhelmholtz  , seriously.  Over the years ll my money actualld did go to digital and sometimes I am still thinking I screwed up, so it does me good to read something such as what you typed.