Thiel Owners

coop_301

The preamp or no preamp , powered preamp or passive preamp conversation has been discused more than once on Audiogons forums .

There is no right or wrong answer , unless as Tom pointed out if you have long interconnects then you need a powered preamp .

Think of it this way , if you are only using a DAC that has a volume control then go directly to the amp , why spend money on a preamp and another set of interconnects ?  Spend your money on Upgrading the interconnects from your DAC to the amp ,  just my opinion .

Have fun reading 219 pages , lots of good info .

@coop-301, @vair68robert offers good advice. This is a subject that has garnered a lot of conversation. As your building your system presently, I'll try to give you the skinny. Please realize that this is somewhat incomplete.

First of all, if you have analog sources, you're probably better off with an active pre.

Ideally you'd have a digital source with a voltage output equal to your amps input voltage sensitivity for full output.  Having less voltage output will negate getting all the clean power your amp is capable of producing. Having too much voltage output will increase the chance of bit stripping through volume attenuation. Having an equal voltage output/input will allow less fussy full range of the volume control.

It would be better to have a digital source with built in volume control than using an external passive pre. Having a digital source with extra bits available (such as with the now ubiquitous 32 bit chips)  to handle the volume attenuation will negate the chances of bit stripping.

It is better to use low capacitance interconnects (more likely with shorter ones) between digital source and amplification.

With the ML 23.5 with its 2.25 V input sensitivity it's more likely that with most typical 2 V (for CD) - 2.2V (for HDCD) digital sources that the lower voltage output via single RCA outputs will better avoid excessive attenuation that could lead to bit stripping, but will reduce the full clean power output potential.  With the typical 4V (for CD) - 4.4V (for HDCD) balanced XLR output you'll get greater noise rejection, full power output from your amp, but with the necessary volume attenuation required you'll increase the chances of bit stripping.

FYI, if I recall correctly the ML needs somewhat unique Camac connectors on the interconnects for RCA input.

Other considerations, most external DACs unlike many all-in-one players are incapable of playing SACDs natively. While there are now many affordable DACs that can equal or outperform units from the past, currently the cost of dedicated disc transports tends to be somewhat expensive. The best value might be in an all-in-one player that has digital inputs that can serve as a hub for additional digital sources such as a streamer.

The above is in reference to "ideals". One doesn't need to match everything exactly in order to achieve satisfactory results. There is some wiggle room, particularly when using the above-mentioned DACs with extra available bits. Such a system if carefully put together to be compatible can not only offer terrific value it can also offer perhaps the purest sounding one. Some, however prefer to add a bit of flavor to the mix. FWIW, IMHO those that want to add something to the mix might be better served with a high-quality equalizer. YMMV.

@unsound ​​@vair68robert 
  Great insight you all are offering, your patience with the noob here is greatly appreciated!  I have to agree that in this case, the pre amp seems like a superfluous addition, I think the DAC pre will work great for my purposes.  Unsound, thanks for the real-world example about the voltage matching, I've seen references to that concept before on youtube that left me with some head scratching, but your example drove it home nicely.  

219 pages...maybe we could throw some chapter markings in here or something!

@coop_301, After re-reading my last post, I realized that I failed to mention that the recommendation to use a DAC with internal volume control vs. an out board passive pre was predicated on using a DAC with extra available bits (such as the 32-bit chip equipped DACs alluded to). If one were to use a 16 or even 20-bit DAC (as is typical with most R2R DACS), analog volume attenuation (typically though not necessarily through an outboard passive pre) would probably be better to avoid bit stripping. That how-ever adds other considerations, especially with regard to interconnects as suggested by @tomthiel.