I’m using the RCA jacks on the back of the DAC. Pre-amp doesn’t have balanced inputs.
Now that’s strange, because IFI specs imply 2.1V in fixed output and 3.3V in variable @ 100%
Since the IFI potentiometer balance seems to be a problem, your solution may be building your own voltage dividers with resistors inside cinch connectors…
Or, I can just get past “mental gymnastics” of caring so much, especially considering I’m already doing convolution filters and house curves in DSP… and my testing thus far shows still having awesome sound quality with Headroom Management set to -21dB… and great convenience of a remote control for volume from my optimal seat. 
And even more oddly, testing again, the volume is slightly LOWER at variable 100% versus fixed… which contradicts the Zen DAC specs.
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Wouldn’t bother me to use the 64bit algorithm for attenuation.
Even attenuating full red book 96db there would still be 48bit precision left.
If you don’t like the small amount of control attenuator adjustment in your preamp you have several options. Change the attenuator in you’re preamp, I guessing powered remote volume on the Parasound more than likely a Alps attenuator, not very good option. You could tape monitor out with no gain if that available.
My recommendation is go to https://goldpt.com/sa2.html and purchase a passive attenuator they make all kinds, very high quality surface mount thin film resistors. The web site is very descriptive and they show the construction quality of their assemblies top notch components.
A higher the resistance pot will lessen the load on the preamp but will create more terminal noise. You also need to look the the input resistance to your powered speaker. If the input resistance of the speakers amp is to low like 10K you will need a higher resistance at least 25k to 50K. If you talk to the folks at Gold Point they should be able to steer you down the correct path and they do custom stuff.
Lot of luck
Another option are these attenuators, that can be placed at the inputs of your pre amp or your Logans. They are cheap, so easy to experiment with.
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My simple logic tells me that attenuating in DSP at 64bit “must surely” be cleaner/better/purer than adding another piece of hardware in the mix no? Especially if DSP is a foregone conclusion since I’m using convolution filters and often playing around with DSP upsampling to DSD?
Any time you adjust the attenuation with a DSP you get phase shift and some digital noise. Resisters have no phase shift and don’t have digital noise. that my two cents
If I were in your position, I would indeed use Roon’s DSP. The Rothwell attenuators are, however, widely used and cheap. If you want to keep volume control in the analogue domain, they might be useful.
They are however fixed so you need to pick them at the right level or have a range on hand to play with. Certainly DSP is free at least in terms of effort to try and use.
This is an interesting thread, but just to play devil’s advocate it seems like a lot of horsing around to get a $130 Zen DAC a remote control.
Why not just get an inexpensive Topping or SMSL DAC with a remote and sell or repurpose the Zen DAC?
Very valid points. I bought two inexpensive DACs as I got into Roon… the rest of the gear I had already, including the Parasound pre-amp that was unused in my closet for years. So it’s a mostly playing around with existing/free options to maximize convenience/quality without buying new gear, learning about what you can/should do with DSP, etc… I’m also intrigued by the thought of dual-purposing my pre-amp by the use of the line-level TAPE REC outputs to feed my analog input Gilmore headphone amp so at the same desk, I can have the speakers turned down/off while using my headphone amp through the same source (with a different convolution filter for the Sennheiser HD600).
The other DAC is a iFi Hip DAC that I have as a portable listening station for around the house, with it’s own Ropieee and battery.
Totally understand. I agree it makes sense to try and use what you already have.
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I had a similar issue. Sound quality was improved with the use of a decent pre amp but I had too little control of the volume as the fixed output level from my DAC to the pre amp was too high. Rothwell attenuators worked well enough but the pair I had available did not give the ideal amount of attenuation and I didn’t want to sink more funds into another set. I found a TC Electronic Level Pilot to be a worthwhile solution. It does require that you have balanced connectors on the Dac and Pre Amp.
https://www.tcelectronic.com/product.html?modelCode=P0C32
There are some available cheaply on ebay (in the UK at least).
I’d go with digital for this reason alone, if you’re already processing the “perfect” bits then do the rest of the job here, one stop.
If you do want a separate gain control and possible signal splitter I’ve used a Tisbury passive for a few years. Decent quality, and not silly money.
Good luck
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Use DSP level control in oder to make best use fo what you have. Calculated at 64 bit float, output at 32 bit to DAC when possible (except in MQA mode where it seems to be 24 bit instead - an MQA signalling limitation I believe).
Device volume depends on the specific device. Some devices have digitally controlled analog volume (many AVRs and digitally controlled amps), some have internal DSP (DACs, streamers). I believe in the case of recent ESS sabre based devices that will be 32bit DSP.
If you want Roon integrated analog volume control - then you will need some some means of controlling whatever device is responsible for volume control from Roon, so an extension for the device (available for some devices, especially some AVRs), or an extension to support IR/network control of the amp/pre-amp device (available for pretty much anything via logitech harmony hub and the deep harmony extension).
Reasons not to do volume control in the digital domain are around how smooth the change in volume is and how much noise is induced as a consequence of whatever dithering is used to achieve whatever final bit depth is output and the resulting S/N ration which is a consequence of the attenuation amount and the bit depth to the DAC and the behaviour of the device at switch on (max volume into an amp is annoying and potentially damaging). Noise is most noticeably an issue with truncated output (especially if 16 bit to the DAC) and/or poor quality dither algorithms (neither of which Roon suffers from and neither of which do good DACs with 32 bit DSP pipelines suffer from).
This could be a cheaper option. https://www.schiit.com/products/sys The reviews are good and Schiit makes good gear.