Looking to completely overhaul my preamp section, knowledgeable people needed!

With recent experience and discoveries, I would avoid stuff with switching power supplies such as the Mytek Brooklyn or Benchmark dacs.   I have been in close communication with another user (robelvick) who initially went with a Benchmark DAC2 HGC and then moved over to a PS Audio Stellar Gain.  The Stellar Gain was a significant upgrade in sound quality.  The Benchmark has switching power supply with op amps, while the Stellar Gain is linear power supply with discrete Class A analog stages.  The difference is significant.  I have not personally heard the Stellar Gain, but my experiences with different topologies in general would agree that the Stellar Gain is superior.

I'm sure there are several available options, but the Stellar Gain would be an excellent choice.  The Parasound P7 is very nice, but it will not be as good as the Stellar Gain.  However, the P7 does have a phono preamp built into it.

Another option would be to look at some of the Audio-GD balanced DAC/premps, such as NFB-27.77.  Like Stellar Gain, it will be a superior DAC/preamp, but you will still need an off-board phono preamp.

The Adcom 555 is definitely a serious weak link here, so upgrading the amp is an excellent idea.

I have looked and worked extensively with Emotiva products. Yes, they are an excellent value for the price point. They do have very good design on their topology and layout. The downside is they use lower cost components to provide that "price point". The amps are good with fuse replacements. The preamp/DAC devices will typically sound closed in. The XSP-1 does have one fully balanced and fully discrete gain stage. However, the input and output stages are littered with op amps. Emotiva likes to use the opa2134, which is a very muddy sounding op amp, in my opinion. If you are limited on your budget and need all the features that the XSP provides (i.e. phono preamp, crossover bass management, XLR, processor loop), it may be a good deal for you. However, there are better choices in equipment out there. If I had to get the XSP, I would look for a "Gen 1" model and then mod the heck out of the power supply and op amps.

The Shitt Freya is likely to be more transparent in sound and resolution if you use the JFET mode, but it purely a line stage without any additional features. Also, tube sonic signature is a whole different ballgame.

I have not heard the Audio GD products, but they have a very positive feedback on other forums and review sites.  The general sonic signature seems to be very natural sounding without any harshness.  The different product lines relate to the type of DAC chip used.  They still have DACs that use the old PCM1704 ladder-based DAC chip.  They also have a new discrete R-2R resistor ladder DAC.  The product I mentioned above uses the new ESS Sabre 9038 pro DAC chips.

Here's a nice review that also talks about the internal architecture:

https://www.youtube.com/watch?v=W0VRkcPMqg4

I brought up the Audio GD option because I think they have an excellent architecture.  Three fully independent linear power supplies for the digital section as well as each of the analog channels.  Nice large power supply capacitance with a lot of local capacitance next to the analog circuits.  Excellent digital clock selection.  Thick metal walls for isolating transformers and digital/audio sections.  Fully discrete Class A FET based analog output stages.

They are made in China and you have to order direct from China.  You can sometimes find a used Audio-GD item up for sale, but they are rare. The NFB-27.77 would be a very nice DAC/preamp.

As far as the discussion on the Emotiva XSP-1, I think I would rather get the Parasound P7.  The quality of the internal components (capacitors, etc.) are going to be much better on the Parasound.  It does have a phono preamp, but obviously it is missing a DAC.