This engineer could have just stuck with the Gateway 2000-branded, Altec Lansing-designed powered speaker set long plugged into his laptop’s headphone jack. But where’s the fun in that?

Having editorially teased my recent home office audio system upgrade several times now, beginning back in mid-August and repeatedly accompanied by promises to share full details “soon”, I figured I’d better get to writing “now” before I ended up with a reader riot on my hands. Let’s start with the “stack” to the right of my laptop, a photo of which I’ve shared before:

The unbalanced (i.e., single-ended) setup

At the bottom is a Schiit Modi Multibit 1 DAC, my teardown of which was published just last month:

Above it is Schiit’s first-generation Loki Mini four-band equalizer (versus the second-generation Loki Mini+ successor shown below, which looks identical from the outside save for altered verbiage on the back panel sticker). I decided to include it versus relying solely on software EQ since I intended to use the setup to listen to more than just computer-based audio sources.

Above it is a passive (unpowered) switch, the Schiit Sys, that enables me to select between two inputs prior to routing the audio to the Rekkr power amplifier set connected to the speakers:

And at the very top is a Schiit Vali 2++ (PDF) tube-based headphone amplifier, identical to the Vali 2+ precursor (introduced in 2000 and shown below) save for a supply constraint-compelled transition to a different tube family:

And the rack? It’s a stacked combo of two (to give me the necessary number of shelves) Topping Acrylic Racks, available both directly from the China-based manufacturer (mind the tariffs!) and from retailers such as Apos in the United States. A little pricey ($39 each), but it makes me smile every time I look at it, which is priceless…or at least that’s how I rationalized the purchase!

Audio sources and interconnects

As you’ve likely already noticed, this setup uses mainstream unbalanced (i.e., single-ended) RCA cabling. To detail the inter-device connections, let’s start with the device at the end of the chain, the Sys switch. I didn’t initially include it in the stack but then realized I didn’t want to have to turn on the Vali 2++ each time I wanted to listen to music over the speakers (whenever the headphone jack isn’t in use, the Vali 2++ passes input audio directly through to its back panel outputs), given that tubes have limited operating life and replacements are challenging at best to source. As such, while one Sys input set comes from the Vali 2++, the other is directly sourced from the analog “headphone jack” audio output built into my docking station, which is tethered to the laptop (an Intel-based 2020 13” Apple MacBook Pro) over a Thunderbolt 3 connection:

Headphone outputs have passably comparable power specs to the line-level outputs that would normally connect to the Sys switch inputs (and from there to an audio power amplifier’s inputs), with two key qualifiers:

• They’re intended to drive comparatively low-impedance headphones, not high-impedance audio inputs, and
• Given that they integrate a modest audio amplifier circuit, you need to be restrained in your use of the volume setting controlling that audio amplifier to avoid overdriving whatever non-headphone input set they’re connected to in this alternative case.

The only other downside is that since the Sys is at the end of the chain, audio sourced from the docking station’s headphone jack also bypasses the Loki Mini’s hardware EQ facilities, although since it’s always computer-originated in this particular situation, software-based tone controls such those built into Rogue Amoeba’s SoundSource utility for Macs or the open-source Equalizer EPO for Windows systems can provide a passable substitute.

Speaking of EQ, and working backwards in the chain, the Vali 2++ audio inputs are connected to the Loki Mini equalizer outputs, and the Loki Mini inputs are connected to the Modi Multibit 1 DAC outputs. And what of the DAC’s inputs? There are three available possibilities, one of which (optical S/PDIF) is currently unused.

It’s a shame that Apple phased out integrated optical S/PDIF output facilities after 2016; otherwise, I’d use them to tether the DAC to the 2018 Intel-based Apple Mac mini to the right of this stack. Unsurprisingly to you, likely, the USB input is also connected to the laptop, again via the Thunderbolt 3 docking station intermediary (albeit digitally this time). And what about the DAC’s coaxial (RCA) digital input? I’ll save that for part two next time.

The balanced alternative

Now, let’s look to the left of the laptop:

You’ve actually already seen one of the three members of this particular stack a couple of times before, albeit in a dustier and generally more disorganized fashion:

It’s now tidied up with an even pricier ($219) multi-shelf (and aluminum-based this time) rack, the Topping SR2 (here again are manufacturer and retail-partner links):

As before, the headphone amplifier is still the Drop + THX AAA 789:

But I’ve subsequently swapped out Topping’s D10 Balanced DAC:

for a Drop + Grace Design Standard DAC Balanced to assemble a Drop-branded duo:

The Topping D10 Balanced DAC is back in storage for now; I plan to eventually pair it with a S.M.S.L. SO200 THX AAA-888 Balanced Headphone Amplifier (yes, it really is slanted in shape):

And yes, I realize how abundantly blessed I am to have access to all this audio tech toy excess!

As you’ve likely already ascertained from the images (and if not that, the “Balanced” portion of the second product’s name), this particular setup instead leverages balanced interconnect, both XLR- and TRS-implemented. As such, I couldn’t merge another Schiit Loki Mini or Mini+ equalizer into the mix. Instead, I went with the balanced, six-band Schiit Lokius bigger sibling:

The Lokius EQ sits between the DAC and the headphone amplifier. The DAC’s USB input can connect to one of several nearby computers. On the one hand, this is convenient because the DAC is self-powered by that same USB connection. On the other, I’ve noticed that it sometimes picks up audible albeit low-level interference from the USB outputs of my Microsoft Surface Pro 7+ laptop (that said, no such similar issues exist with my Apple M2 Pro Mac Studio).

And what of the DAC’s optical S/PDIF input? Again, you’ll need to wait until next time for the reveal. Finally, in this case, the headphone amplifier doesn’t have pass-through outputs for direct connection to a stereo power amplifier (or, in this case, monoblock pair), so I’m instead (again, sparingly) leveraging its unbalanced headphone output.

The rest of the story

So far, we’ve covered the two stacks’ details. But what does each’s remaining S/PDIF DAC input connect to? And to what do they connect on the output end, and how? Stay tuned for part 2 to come next for the answers to these questions, along with other coverage topics. And until then, please share your so-far thoughts with your fellow readers and me in the comments!

—Brian Dipert is the Principal at Sierra Media and a former technical editor at EDN Magazine, where he still regularly contributes as a freelancer.

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