Jeff Rowlands Amp and Dac vs. VAC amp and DAC


Hello, I am new to this forum but I have a question. I am trying to pair an amp + DAC with my Wilson Sabrinas. I have listened to Jeff Rowlands integrated with the Aeris DAC. And the VAC Sigma integrated with the Aeris DAC. Price is a factor and so is space. Does the 625 need a pre-amp? Any suggestions or thoughts? 
rinpoche
I have all Jeff Rowland components(625 S2, Corus preamp, Aeris DAC) driving Monitor Audio PL500s. Despite what anyone says, there aren’t any absolutes in Audio; let your own ears decide.

I had the Continuum S2 integrated amp and now the 625 S2. I submit the 625 S2 is a decent step-up from the Continuum S2 that should be easily heard, but relatively expensive. You can use the Aeris DAC to drive the 625 or use a preamp.
I have heard the vac integrated at length and it is a great amp. I also prefer tubes over ss for the Wilsons
Alan
I hope you will indulge me a bit here. I have heard the VAC Sigma 160iSE and the JR 625 upgrade both with the Aeris as the DAC. I am a bit nervous about tubes. This would be my first time with a tube amp. I do agree that the VAC is amazing. The JR is also good and it is a bit easier given it is plug and play and no tweaking, changing tubes, etc. is required -- so are tubes really difficult? Is the sound worth it? I agree that the VAC is fabulous but the JR is also very nice. Please say more on the topic if you can? 
You said it yourself. If you want fabulous get the Vac. If you want very nice get the Rowland. Vac amps are pretty much plug and play
Alan