Meridian 568 v ARC Tube preamp for digital scource

My current set up is: Meridian 508.24/Meridian 568.1/ARC VT100 MkIII/Proac Response 2, running as a balanced system. In the current set up, I'm using the 568.1 as a 2 channel preamp. It gets a digital feed from the 508.24 and provides upsampling to 96MHz. On its own the 508.24 gives 24 bit processing, but no upsampling. I'm thinking of getting an ARC Line Stage with balanced connections (LS16, LS17) to replace the 568.1. Any comments about what I could expect from making this change and/or which ARC Line Stage is more suitable if I make the change?
In my system I had an 861 which I used as a DAC/PRE as you are, then added an ARC LS26 and found it to be a large improvement.

If you need a processor to serve as a 2-channel pre-amp I'd say Meridian is near the top of the heap, but it still falls well short of a dedicated 2-channel pre-amp in my experience.

What I gained? Improved sound-stage (width and especially depth) as well as texture - specifically in the midrange/vocals.

If you can being one home to compare I think you will find your answer quickly. Good luck with the search!
The ARC LS 17 is a very good pre but do be aware-- it does NOT sound tubey. I owned and sold one because I wanted just a touch more sugar in the sound. The LS 17 and likely by extension the 6H30 tubed LS 26, will be fairly exacting in their presentation. This is not bad-- it's great actually -- for some-- but see if it's your cup of tea.
In my experience the primary thing you gain by adding a linestage in your situation is dynamics followed by perhaps more refinement up top.
Abramsmatch..which ARC preamp would you recommend that has a bit of a tubey sound ?
Jim - Thanks for your input. I suspected that I might need to go that way to get the optimal sound and I can only think that if the 861 wasn't up to it, the difference with the 568 would be even more pronounced. BTW I checked out your system. Looks phenomenal!

Abramsmatch - Thanks for your comments about the LS17. I think the VT 100 is fairly revealing so something tubier in the preamp might work, but I'll need to hear it before deciding. What would you recommend in the ARC range (balanced) in this respect? Maybe the LS16 MkII?
My setup is a Meridian 568.2, Aesthetix Calypso, Theta Dreadnaught 1, Thiel cs1.5. You will find that a tube pre will improve the depth and width of the soundstage. It will also improve sound of strings and voices. Good Luck.