So here is my scenario.  I have a Rega P3-24 w/ an Elys 2 cartridge and it is input directly to the phono stage of my Marantz AV7005.  It sounds temendous.  Nice, warm, full sound. Completely quiet and idiot-proof to set up.  Only issue is, relative to other sources, it is not very loud.  

I just purchase a Rega Brio R for my living room and I am trying to decide what to do.  My understanding is there is a real serious benefit to pairing a Rega turntable and cartridge with that Brio R.  

Initial plan was to get an RP1 w/ upgrade kit.  However, I am concerned taking a step back as it sounds like the RP1 has some weaknesses that I may not like.  

I am considering getting an RP3 with an Elys 2 and swapping it into the main system and moving the P3-24 to the Brio R.  However, the world is open to me if I move the P3-24 as I don't need a Rega to Marantz pairing.  

Given this scenario, what to do?  RP3 w/ Elys 2 or potentially a higher end cartridge like the Exact 2 or the Ortofon 2M Bronze or Black.  RP6 w/ the Exact 2 or the Clearaudio Concept w/ base cartridge or Ortofon 2M Blue and dust cover.  I want to keep this under $2000 in total spend.  

One final option would be RP3 w/ Elys 2 and an external Rega Phono Stage and the external Power Supply.  

What is gonna give me the most bang for the buck?  Should I be concerned about an external phono stage?  Will that external power supply make a noteworthy difference?  Is the cartridge more important than the phono stage or the deck itself?  The Ortofon cartridges appear to be lower output than the Regas.  Will that exacerbate my volume "issue?"

Lots of questions.  A little guidance to help me refine where I should focus would be helpful.  

Thanks in advance.