the best, cost-no-object, music streamer?

Define streaming device. There are so many different architectures to get digital audio files into a Dac these days. What functionality are you looking for in the device. Storage? Library management? D/A conversion?

There are some interesting high end options available these days. One is Boulder. The 1021 also allows you to spin discs, but not no other digital inputs.

http://www.boulderamp.com/1021-p1.html

Another option is the new Weiss MAN201.

http://www.weiss-highend.ch/man301/index.html

But are very high end players. There are probably a few others, since this is a becoming a pretty hot market segmens, as more and more real high end oriented folks are moving away from spinning disc, but are intimidate by the prospect of having to build their own Mac or PC based system.

I don't know the sooloos, but I think some of it's competitive advantate was in the library management and user interface features.

I suspect with the advent of iPads, a lot of manufacturers can put together a very decent user interface, and may be superior stictly from a sound quality perspective, using their latest technology.

There are a lot of ways to architect a network based system . The term "streaming" is no used consistently. The weiss MAN201 supports streaming (i.e. plays music files coming in over ethernet). The PS Audio Perfectwave bridge does as well.

However, any music server (such as the Bryston BPD 2) that can access data stored on a NAS is not technically streaming, but for practical purposes this makes little difference.

The options are many, and there are an increasing numbers of the high end guys offering very expensive and presumably good systems.

The list of contenders for "best streamer / server" keeps growing, which just underscores this is an emerging new segment with lots of new products hitting the market.

The trigger is really the coming of age of computer audio, to the point where die hard audiophile disc spinners are ready to jump ship.

Let me add to the list of high end streamers the audio research media bridge.

http://www.stereophile.com/content/audio-research-reference-dac-digital-media-bridge

The USB input on the McIntosh is asynchronous, so you are effectively using the clock on the c48. When you put a very good USB converter between the c48 and the Mac, the clock in the USB converter will provide the masterclock to the c48 instead (assuming the S/PDIF inputs are synchronous). It is conceivable this will sound better, but not a foregone conclusion. Only way to find out is to try. You could get one of Steve's Offramp 5 converters. I believe he has 30 day return policy, so if you hear no impovement you send it back.