How important is a preamp for purely digital sources?

Cables, are mostly snake oil, and differences are the most minute of any part of the audio chain, and are particularly small compared to those of the speakers. Don't understand why companies aren't being charged with fraud for making false claims about boutique cables. What's George Cardas new product now, the, "Cardas Clear Power Cable is George Cardas’ midrange Clear-series AC power cable.", which, "is designed for applications where you need a bit more current capacity and a higher degree of filtration than Clear M Power Cable, but you don't need a large, high-current power cable like Cardas Clear Beyond." Interconnect differences are inaudible for 95% of the general population if the connectors are clean and the wiring doesn’t add capacitance, or inductance. On the other hand, somebody would easily be able to tell that my power amp is on the warm side. If the system has EMI that happens to be picked up by the interconnects, then it's best to deal with that at the source. I have DH Labs Silver Sonic BL-1 Series II interconnects that I made myself specifically so I could make them as short as possible, and have heard zero difference compared to OEM cables, particularly with the short lengths that I use. It’s still available for $7 a ft on Ebay, and the ad says, "SILVER SONIC BL-1 Series II Interconnect is a high performance audio interconnect cable that combines the highest sound quality and reliability available at its price point. " Sure. Whatever that means. It's designed as balanced, and comes with a shield, but I don't use XLR in my system; my amp and sub can't do it. XLR had been designed for professional applications, to reject interference for the longer cables runs used in the field, and this could add little value to most amateurs.  People can reduce noise, by keeping cable runs short and away from noisy things like motors and VFD's. I have also used some BL-1 inside my power amp and that's the only place I’ve grounded the shield (it's a noisy power supply). You can use twisted pair cables to try and reject interference, but again, there's little of that in my system away from the power supplies. People can use ferrite beads or rings from Digikey to reject EMI in a a DAC or amp, or better yet, peel and stick foil. I have used it to try and keep power supply noise away from other parts of the circuitry. I can't detect how bad it is without an oscilloscope.

dookie30:

Take a look at a McIntosh D150 or perhaps a D100. My be a little bit more than you are want to spend but consider the axiom of buy it once and save in the long run.

I owned a D150 till I upgrade to a D1100 which I run now. The D150 will mate will with your Mac amp. Use the resonable S/PDIF out to the D150  from you Node and a decent set of analog lines to the amp. The D150 will perform volume in the analog domain. 

One thing that is rarely discussed with DACs is the analog output section. This is very import to the overall sound and vibe of the DAC (in this case digital preamp) and what works for one might not be a good choice for another. That said, since you have a McIntosh amp you might like the overall synergy from the two pieces. Also, if you want you can hook up other digital sources as well as a McIntosh CD/SACD transport where the DSD will be connected via a custom DIN connector. 

Very happy with my setup and the D150 seems to be going for around $1.5k to 1.8k these days. Find a nice one and be happy.

A preamplifier vs direct to amp to dac ,a good preamp always better especially a vacuum tube preamp

Any stage can only distort. You may liek the euphonic distortion of a tube preamp though, which is valid

t allowsbettrr dynamics
soundstage depth as well as image depth .good power supplies
and transformers give you the amplified dynamics ,

You cannot add dynamics (not without DBX like expansion). So this is false. maybe for some reason the poster gets the subjective impression of dynamics - louder maybe. We all know the Fletcher-muson effect. (e.g.: the loudness button!)

preamplifier it takes the signal and amplifies the signal.

Well, yea, superficially, but 99% of the time a preamp is actually delivering fractional gain (its only attenuating the signal).  If this were nto true you would nto have the option of driving the amp with the DAC at all!
obviously, if the DAC does nto have a high enough output level, you need a preamp.  I presume the OP knows otherwise.
What a preamp CAN do is fix impedance matching issues. if the DAC has a hgih impedance output, and the amp a low impedance input, you Will lose dynamics and a preamp might fix this. With well designed equipment this ought to be rare.
G

This is turning out to be very interesting ...

I'm currently at a stage where i'm still experimenting.  I've been using a 7.2 receiver for so many years and I want to explore a purely audio setup for now as I appreciate music more than movies.

The upgrade itch hits once in a while and I've been weighing if I'll be getting a pre-amp or a DAC and I'm leaning more into a pre-amp. 
  
Just a follow up question to the DAC ... it seems that DAC technology is constantly improving and there's a big possibility that a very good DAC today may be outdated in the next few years.  Is this the case? 

Interesting discussion. I've been running a modified Oppo 203 (digital only) to a Lampi Atlantic TRP dac, and then directly to ATC SCM19A floorstanding actives (and soon JL Audio e-110 subs). The ATC's are balanced but I'm using faux balance, i.e., unbalanced, out of the Lampi. Before the Lampi, I used a Directstream dac from the balanced ports for a few years. Since getting the Lampi, everyone I speak with, users and developers, say I'll get more out of it with a good tube preamp in there. Most of the ones I've been looking at are in the $3700-$4800 range new, which is out of my range at the moment (Rogue RP-7, Linear Tube Audio M3Z, Wells Commander, PrimaLuna Evo 400), so I've been eyeing eyeing PrimaLuna Dialogue's on the used market, which look like they can be had (with bargaining) for around two bills. I came across the Schiit Freya+ mentions today and read reviews and user comments, but I don't think it matches up with the PrimaLuna in any fashion except having XLR outputs and much lower cost. I should also say that I like a modestly warm (but not lush) sound, something emotionally engaging with the music rather than the "sound." Other suggestions or thoughts?