Is a separate phono pre really necessary?

I've had a few preamps with a built-in phono: Rogue Magnum 99, BAT VK-30, Plinius MP16-P, and Audible Illusions M3B.

All those built-in phonos were just OK, but not comparable to Allnic H1202 and Magi phonomenal in my system,

Magi is actually better than MM of Allnic.  Magi + Sound Tradition SUT is better than MC of Allnic.

My cartridges are Ortofon MC20 super, Ortogn SPUs, Denon DL103, AT150 mlx, ...

Not all $1000-$2000 phono pres are equal. Some may be just about the same as your built-in phono. Magi costs $1000, but I am not sure whether it is still being made.

For 2k the Gold Note PH-10 is an amazing, very flexible phono pre. Should work with almost any cartridge MM or MC because of its flexibility. Do a search you will find over a dozen reviews online. Sound wise I love it!

I prefer a tubed phono stage, so i opt for a separate. There are not too many tubed phono stages built into integrated amps. Most use the tubes in the line out sections only. 

While the phonostage in my Luxman L-509x is no slouch and is actually very good, my recently aquired Sutherland Insight LPS MM/MC phonostage preamplifier is a definite upgrade in terms of bass response, clarity, detail retrieval, etc. Might be a touch drier than the Luxman but the Sutherland's dynamics are impressive and sometimes startling.

The Phonostage is critical to the performance of a turntable. I recommend a tubed Phonostage. But also would wait until you can afford more than $2K maybe $3K. Then go for a used Phonostage… I recommend looking at Audio Reseach, Conrad Johnson, or VAC… these are amazingly great sounding and will last forever. Presto is a newer contender.

I went through increasingly expensive phonostages until moving into the $5K new range. There is a very significant benefit to getting into the $5-10K range and used you can do that for maybe half. Can’t just be any phono stage in this price range it needs to be carefully chosen for its sound.