Gustard V18 vs. Allo Katana - a 2022 assessment

For almost a year or so I am running an IMO excellent Gustard A18 DAC.  The Gustard builds around the top of the line AKM AK4499 and Accusilicon clocks.  The DAC received quite some nice reviews confirming my experience with it.  Most reviewers saw that DAC challenging much pricier rivals. Until now I was never in doubt about the overall DAC performance...

Before Gustard I was running a tweaked Khadas Toneboard1. And before that plenty of tweaked RPI HATs. In between I listened to this or that (incl. high-end gear) to see where I am standing. 

Over the last year I applied - I had to - plenty of tweaks to get this rather nice Gustard DAC setup working satisfactory. You might have seen it in my "my system" section.

What I did:

1. power cable swap
2. fuse swap
3. applying USB filters and isolators
4. using a new USB cable
5. applied lots of RPi OS optimizations
6. applied some RPi HW modifications
7. Changed the DAC default settings

Basically all the stuff you'd do with most DACs out there. All this lifted the DAC into a different arena.
Without all these tweaks applied I always had the feeling my "tweaked" Khadas was able to rival a stock Gustard. 

After all I concluded that the Gustard A18 device -- with all tweaks applied -- is an excellent performer. I am running the DAC differential right into a Purifi - Eigentakt amp. These devices mate extremely well. Volume control is done via software. Bottom line. I love this setup. I enjoy(ed) every minute with it.

However. Yep. Here it comes.

While cleaning up my lab the other day I stepped over my Allo Katana HAT. It's been settling dust for quite some time (years). The Katana is no longer built/sold. It used to be an around $250 device.
As a matter of fact it mates well with the RPi4 family, despite its docs showing RPi3 support only!

The Katana comes with an excellent Sparkos-Labs discrete Class-A output-stage and requires multiple high quality rock solid  5V supplies - if "excellent audio performance" is among your targets. The Katana is built around a rather entry level ESS Sabre 9023 DAC - implemented the Allo way though. Allo tried to tweak most out this DAC. If you look at the 3 boards closely you'll see how much complexity Allo built into this tiny stack to accomplish their goal to create a great performing "class leading" HAT DAC. 

During those early Katana days I considered the Katana a solid performer, offering (requiring) a bit too many "power options".  I used it for testing and documentation purposes. I never really used the DAC in my systems.

Today, some years further down the road, probably bored by that well performing Gustard/Purifi system, I thought why not give the Katana a try once more. Just to see where I stand with my USB-DAC stuff. I didn't expect it to become a huge effort to get it hooked up. The task required a bit of reshuffling. I soldered differential cables to the DAC. Attached some power supplies. Had to reprogram my PI setup to cope with DAC specifics. T'was done in an hour or two.

What struck me first:  No more annoying and expensive USB tweaks. What a relieve!

For now I have 3 5V supplies attached. 1 (iPower) for the USB-SSD, 1 (Shanti) for the PI4 and 1 (Shanti) for the DAC.

According to Allo it requires at least one more rail for great sound. And then I do not have an isolator in place. I read reviews claiming an isolator was making things worse with the Katana. That's not gonna be up high on my priority list.  Anyhow. It looks there's further tweak potential out there.

I run the DAC with its linear filter and on-DAC volume control on my own RPi OS. Just to mention it.

Last night I finally powered Katana up for the first time in years. I gave it some time to settle and to  warm up. Class-A loves stable conditions.

Allo recommends to power up the audio stack first! Luckily I have my DC rails attached to relays and Wifi (DIY home automation based on Arduino/Tasmota/iOS).
I can simply shout  a "Hey Siri" "Stereo ON" and magically all devices (rails)  turn on in the right sequence and timing.
(Ok.Ok. Not much magic here. Just technology) 

I then pressed the "Play" button on one of my fav tracks expecting nothing... 

... and nothing...   ...but clean and dynamic sound hit my face.

Oh boy. 

I wasn't expecting that.  I couldn't localize any obvious downside. Nice. It all sounded so familiar to what I've been listening to for a while.  Hmmh. Similar - is the better wording. The low end, the highs, the depths and separation, the tone-colors, realism, naturalness, the impact, basically everything seemed to work fine. No booming bass, or sharp Ses. Nice.

After a bit of breaking-in and stabilizing, the DAC developed some more to me obvious (subtle) qualities. It stayed on for the rest of that enjoyable night.

I had no problems to conclude after 3 hours, that even at this early stage I am tempted to rate the Katana performance above my highly tweaked Gustard A18 setup.  Wow. I wasn't expecting that. For sure this little project was well worth the 2h effort.

During the coming days/weeks I'll put some more effort into the project. If I am able to gain even more, unfortunately the Gustard will be gone for sure. 

Aftermath

Folks. I sometimes do get the feeling that I am spinning in circles. I do know I am not alone on that one. I simply realized after almost 4 years that I didn't make any progress on the DAC side.  Actually. It's been the other way around. All new DACs, even after heavy tweaking, I had or tested didn't perform as well as the Katana in the setup I've been listening to last night. Puh.

Let's not talk about the time and money that's been wasted. That's kind of frustrating. But again. I've been enjoying that IMO rather flawless Gustard DAC for quite some time now. Fact is, the differences  between Katana and Gustard for now are not night and day. I could live with either setup. But honestly. The Katana comes with a better feel to it - why ? - successful DIY Audio projects which surpass commercial high quality solutions are simply most satisfying.

Another learning. It seems that the overall DAC evolution approaches some kind of stagnation state.
Which doesn't mean there's no space for improvement. What I mean. All these DAC still heavily respond to upstream improvements and changes. Stagnation exists because most DAC developments just follow that generic "standard specs" path, which we all know is not sufficient to explain the entire soundimage in front of us. 

Some thoughts about Allo - since Allo just made it back into my main focus - I'd like to share. I was rather close to the Allo folks in the early days. Later on things developed into the wrong direction. However. I have to admit Allo did a great job during those days (let's not talk about the Katana callback disaster - Allo usually acted pretty customer focused ). Most of their products were performing above average and were priced quite fair. And for the most part they were listening to the customer base and DIY-Audio community given advise.  The company IMO had huge potential. A pity that it's been pretty quiet around that company for quite some time. Let see if they recover from the plague (chip shortages). Let's hope they'll survive these challenges. There's IMO more to it I guess. Allo IMO should have stayed in the HAT business. By entering the USB segment with the Revolution DAC, they were facing a different and pretty rough and tough competition and lots of pressure. Another highly complex product, the RPI CM3 based Allo USB Bridge, must have been turned out to be a nightmare project for them. A major project.  A major effort. Exactly at the time of the USB Bridge market launch the much better RPi4 showed up. Basically the CM3 and the Allo board could be considered immediately outdated at launch. Really bad luck. I'm also wondering if the newest kid-on-the-block, the Boss 2 project, sells as good as it measures. It's neither a real HAT nor a "Boss". Allo should have marketed it differently. Hifiberry shows how it works: "Stay focused, stay on your turf". Therefore I think, it was not just the ship shortages putting pressure on Allo.
Sorry for talking too much business here. I just hope that Allo finds back to its high quality HAT roots one day.  The Katana simply proves to me now they were on the right track back then. I wish Allo good luck and a more focussed approach with future projects. ;)

Back to my little project. This little exercise just showed that I have another viable audio setup at hand (and best of all - there's still tweak potential).  And instead of jumping on the next "greatest DAC ever" hype or offering I better head down to the basement and continue my DIY efforts. There might be even more hidden treasures down there. 

Enjoy. Stay healthy. Peace.