Audio is better
when you understand what you're hearing.
Systems advice, equipment notes, and DIY projects — written by someone who genuinely loves this stuff and wants to share what they've learned along the way.
Equipment notes, DIY builds, and system advice from someone who's been deep in this hobby for a long time. The goal isn't to tell you what to think — it's to share what's worked, what hasn't, and help you find what sounds good to you.
Explore
Articles & Video
Going deep on the things that matter
Circuit design, system matching, listening observations. Videos covering builds, teardowns, and whatever rabbit hole I'm currently in.
Writing and video on audio topics I find interesting. If it's useful to you too, great.
Featured Article Image
DAC · Chip ComparisonMay 2026
ESS vs AKM — Two Chips, Two Flavors, One Interesting Box
The Douk Audio Q11 does something I haven't seen much of — puts an ESS9038Q2M and an AKM AK4493 in the same box and lets you switch between them while music is playing. I've been using it alongside my Moondrop Dawn portable and it's taught me a lot about what chip character actually means in practice versus what people say about it online.
The Douk Q11 and Moondrop Dawn in the same system. What ESS and AKM chip character actually sounds like, and whether it matters as much as the forums suggest.
Focusrite vs. Universal Audio — Who Actually Wins for Home Studio
22 min · February 2026
Gear
Equipment
Things I own or have spent real time with. Notes on what they do well and where they fall short.
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Amplifier Image
Amplifier · Class A
First Watt F7
Nelson Pass / First Watt
25 watts, single-ended JFET. Needs efficient speakers but when you get the pairing right it's hard to go back to anything else. One of the most enjoyable amps I've had in my system.
★★★★★Owned · 2025–present
🔊
Amp Image
Amplifier · DIY · Class A
ACA Mini
Nelson Pass / diyAudio
5 watts, $25 essentials kit. A fun build and a genuine introduction to Class A amplification. Currently mid-rebuild after a blown channel — see the DIY page for the full story.
★★★★★Built · 2024
💿
DAC Image
DAC · Desktop · Dual Chip
DAC-Q11
Douk Audio
ESS9038Q2M and AKM AK4493 in one box, switchable on the fly. The AKM runs warmer and rounder; the ESS is more open with better perceived width. Both are usable and the comparison is genuinely interesting. Glass top and dual OLEDs look great on a desk.
★★★★☆Owned · 2024–present
🎧
Portable DAC Image
DAC/Amp · Portable
Dawn Pro
Moondrop
Dual Cirrus Logic CS43131, 4.4mm balanced out, 13 grams. Hard to argue with at this price. I use it away from the desk and it competes well above what you'd expect. Use the balanced output if your headphones support it — it makes a difference.
★★★★★Owned · 2024–present
🎛
Preamp Image
Preamplifier · DIY
B1 Buffer Preamp
Nelson Pass / passdiy.com
Unity gain JFET buffer. Gets out of the way. A solid first build if you want something low-stakes to learn on — the PCB is available directly from passdiy.com with matched JFETs.
★★★★☆Built · 2023
🎙
Interface Image
Studio · Interface
Apollo Twin X
Universal Audio
The UAD plugin ecosystem is the real sell here. The preamps are solid and the converters sound good. If you record at home with any regularity it's worth the investment.
★★★★★Owned · 2022–present
Build It
DIY Projects
Parts lists, build guides, upgrade paths, and bias procedures. Written by someone who has made the mistakes so you don't have to.
Featured Build
Nelson Pass DesignMay 2026
ACA Mini — Full Board Rebuild with Upgrades
Complete rebuild after a blown channel. New matched transistors from the diyAudio Essentials Kit, upgraded Nichicon KG output caps, RL8 polymer rail bypass, and a full re-bias walkthrough. Includes the complete Mouser parts list with upgrade notes on every cap and resistor.
Unity gain JFET buffer. Excellent first build. Teaches you impedance matching without a lot of complexity or risk. PCB available from passdiy.com.
Est. Cost~$40–60
Build Time3–4 hours
DesignerNelson Pass
Beginner
ACA Mini — Stock Build
The standard kit build. One afternoon, 5 watts of Class A, and a very good reason to build your next amp. Essential starting point.
Est. Cost~$150 complete
Build Time4–6 hours
DesignerNelson Pass
Intermediate
ACA Mini — Upgraded Build
Same board, better parts. Nichicon KG output cap, RL8 polymer bypass, fresh matched transistors. Meaningful improvement for about $35 over stock.
Est. Cost~$85 w/ essentials
Build Time4–6 hours
DesignerNelson Pass / RSD
Advanced
Zen Amplifier — Variations 9
The full Zen journey. Single gain stage, no feedback, no caps in the signal path. Requires matched MOSFETs, good heatsinking, and patience with the bias procedure.
Est. Cost~$300–500
Build TimeWeekend+
DesignerNelson Pass
Get In Touch
Contact & About
Questions about a build, system advice, or just want to talk audio. Get in touch.
R
Robbie
Founder · RSD Audio
I've been into audio for a long time — through hi-fi, home studio recording, and a fair amount of DIY amp building. I've owned gear across a pretty wide range and built more kits than I can keep track of.
RSD Audio is where I put what I've picked up along the way. It's not a business and I'm not trying to tell anyone what to think. I just love this hobby and find that talking about it and writing about it helps me enjoy it more. If it's useful to you too, great.