built-in phono stages -- good idea?


It seems to me that the best location for a phono stage is at the tone arm wire end -- in the turntable. My thoughts:

This would bring the following benefits to its performance:
Elimination of the sensitive and susceptible phono cable
Reduction of the need for a balanced phono stage
Reduction of noise without the need for balanced design -- half of the battle is won already.

Both are significant advantages, I think. But this puts some limitations on the design of the phono stage:
Needs to be very compact solid state design, probably SMD. Access to loading options and mc/mm switching need to be thought out and accessible from rear or underneath. Again, both doable.


Why don’t we see this more often? Your thoughts?


Herman
gera
Emt tables are built in. I think Walker Audio tables  almost do this  by connecting the arm wire directly to the phono amp. It’s just not convenient enough to be viable option. Even the best design isn’t necessarily easy to market.  
The power supply would be external of course. Only low voltage in the turntable + shield box on the actual compact phono stage.

I don't know... it seems like a good idea to have the amplification as close as possible to the delicate signal source, to reduce the amount of noise being picked up. It is now possible to have compact, high performance phono pre amps thanks to SMD.and good opamps. Just seems logical so I must be missing something ???
The Naim Prefix is one example of a commercial product that is based on those principles.
There is nothing stopping one for placing the phono amp right behind or below the table/arm/cartridge, with an uninterrupted run of internal arm wire from cartridge tags to RCA plugs going right into the phono amp jacks. That's how I and others do it. If you can get the phono amp close enough to the arm, the wire need be only 1/2 meter long.
An interesting idea, but difficult in execution. Ortofon went part of the way there on their early SPU cartridges building a transformer into the headshell. See the excerpt below from the Ortofon wedsite:

"Because of the very low impedance and the very low output, the first SPU cartridge, the SPU-GT, had a small transformer integrated with the cartridge units in the GM- housing, yielding about 7mVolt at 5cm/sec suitable for an MM input sockets with 50kOhm loading. "