Asynchronous USB vs. SPDIF with regard to DAC upgrade

@rossb I had Meitner MA3 in my system. It was a big step up from Bricasti M3 in every parameter.
The latest MA3i is significantly better than the original MA3. It has more substance and body than the original MA3. I never auditioned Weiss so I can’t provide any thoughts on how they compare. 
 

As to your thoughts on computer USB vs a good streamer with optimized USB out such as Aurender N200, there’s no comparison in my opinion. I’ve tested this. Not sure about Lumin U2 - it may be the same as your computer USB out. No experience wit Lumin other than U1 Mini which was nothing special. 
 

@kjl1065 definitely try both Weiss and Berkeley. If you’re loyal to your dealer expect the same in return meaning home audition of both DACs. 

I do not agree with the comment above that it is too detail oriented and analytical. It is neutral and accurate without artificial warmth or bloom, but is full sounding, as well as being musical and engaging.

100% @rossb I don’t understand how people state this. With my DAC 501 mkI I just hear natural and accurately reproduced music, especially jazz. I guess they didn't try the de-esser! (I don't use any DSP tools) 

If @kjl1065 could scrape another 10k and get the Helios he would have one of the best DAC’s on the planet. Michael Lavorgna preferred it to his MU1/TotalDac combo: https://twitteringmachines.com/review-weiss-engineering-helios-reference-dac/

consider a DAC that supports Ethernet and serves as an endpoint. 

The Weiss 501 does: It is a player, having an endpoint/renderer, and it is a good one. Wouldn’t be surprised if it surpasses the Lumin U2 Mini, as comments I have read in the past stated it was comparable to a $5k streamer. 

 My dealer is always there for me and supports everything he sells and is always a phone call away to come to my premises and work on any issue that I may have, I find this invaluable. 

If this is true, then this should be true:

If your dealer sells both of these he should loan them to you for a few days so you can evaluate them for yourself in your system, especially with DACs at this price level.  Full stop. 

@kjl1065 definitely try both Weiss and Berkeley. If you’re loyal to your dealer expect the same in return meaning home audition of both DACs.

That is the only way you are going to do an adequate demo- same gear, same room, same music files, and enough time with each to do a proper evaluation, using the optimum connections for each unit, Lumin vs. Weiss ethernet in etc.  much better than 15 minutes in a strange environment. You are handing your dealer >$5000, I would insist on this. 

Surprised no one mentioned until mclinnguy that the Weiss does not need a streamer, plug it in via Ethernet and run Roon.  Also, note that it was mentioned that one should get a streamer with I2S.  Why do this when the streamer inside the DAC uses I2S.  Short signal path designed by the DAC designer no less.  Lastly, if you read the lengthy thread by Verdant Audio where he rates a lot of DACs, he notes that he had to step up to a very expensive streamer to beat the one inside the Weiss.  So unless you want to use a streamer, the Weiss presents an excellent one-box alternative.  

Also if you follow the general discourse, there seems to be a consensus that computers (as a streamer) are bad and Wi-Fi is bad.  When I bought my first Lumin some years ago at Upscale Audio, they explained to me that Lumin was somewhat unusual in that they believed it was best to get the computer away from the DAC by networking the Lumin (which like the Weiss many of their models are also a streamer/DAC), putting the music files somewhere else on the network.  This can use a simple computer, since whether using a switch or Wi-Fi, the DAC then takes the job of processing the bits (as you mention above regarding USB), including clocking.  I think there’s a lot to be said for this model.  Streamers have become so expensive because they -are- computers.  They now have fancy power supplies, and all kinds of other tech to minimize the damage of having a computer nearby the DAC.  Networking it takes care of a lot or most of that.  So you can use a computer in place of a dedicated streamer, and I would argue, aside from possible dropouts, you can use Wi-Fi here as well since the DAC/streamer is processing and buffering the bits, as long as they get to it.  
 

So as an example use case, you can take an old laptop or desktop you have laying around running Roon (or other software) and holding your music files, attach it via Ethernet to your router or itself via Wi-Fi,  and plug in your streamer/DAC via Ethernet also, whether hardwired or Wi-Fi, and you never need a file server/streamer (like an Aurender).  Yes, people can argue what the best sounding setups are based on many variables, but if you don’t want a separate DAC and audiophile-grade server/streamer (many of which you’re also paying for their software, like aurender or Innuos), this is a workable alternative, and not necessarily a sonic compromise.  

+1 @tubeguy80 

the answer to the OP is “it depends”.  Theory will only get you so far.  I’ve heard many DACs where usb was either the best or the worst option.  And does anyone make asynchronous usb anymore?