E44 laidback? Then this ESS- based dongle is "less glary"?
Sorry, it does not make any sense at all to me!

@PhonoPhi ess-based doesn't mean automatically it's going to sound glary. i have a few other portable sources with 9039q2m (zishan u1, dethonray sg1) and they do not sound glary at all. additionally, amp section makes a bigger difference than dac. two same chips could sound very different depending on amp/op-amps implementation. ks01 does have a dedicated amp chip, while e44, if i understand correctly, does not as it relies on the amp built into its cs chip.
glary to me is more of a technicality which is about audible digital artifacts during playback, especially noticeable on note ends and transitions. while being laid-back, is more of a presentation feature in terms of whether staging is forward sounding or not. the two are not mutually exclusive in my mind. anyway, if you live/work in toronto area i'd be glad to lend you ks01 for a couple of weeks so you can try it for yourself and maybe share some impressions (just pm me).

Thank you for a kind offer. I already managed to order KS1 in my budget dongle shopping spree: DC03 pro, a bunch of JCAlly - new JM6 (balanced and pro) look very promising, CX31993 feels like a best budget chip to me.

I do not question that ESS implementation can be different (I do have 15+ ESS based dacs/amps). I was rather surprised by your E44 assesment, it may be on a colder/brighter side, but no glare compared to brutal ESS implementation, such as in Z4 or Fosi amp (my "native" ESS implementation reference).
I used to be a "ESS fan", but slowly, I got on the Cirrus side, with E44 being my favourite dongle so far. Battery-powered E1DA SG3 is a powerhouse; and Muse M3 offers a nice implementation of 9038 filters, but they are less practical. ESS chips are much less power efficient.

Looking forward to your thoughts on KS01. Let me know if you end up needing firmware/driver links.
I appreciate a variety of flavour, including from the three major ds chip manufacturers. It's like food. If I eat even my favorite meal for few consecutive days, I get sick of it.
I think Cirrus chips are generally under appreciated. There was a lot of heat when they bought Wolfson and switched iPod dac to their own Cirrus. W2, with two 43198, is still my favorite dongle. I also managed to recently snag topping D30pro for my work office which has a rare setup of four 43198 chips in eight-channel stereo configuration. Even my donner em11 with cheap cs4344 can do damage.

Hi, I have one of these arriving soon, where can I find firmware if I need it?

Thanks

@duracell071 I got updated firmware from the Ali seller I bought from. If you cannot get it from your seller, pm me and I'll share it with you.

I got KS1 recently, and less then impressed overall in the first impressions.
First, there are no any labelling as if some OEM product. Then the plastic on side panels is prone to fingerprints and scratches, and a bit concerning for longevity. The aluminum frame is nice. Buttons are firm but hard to operate (at least for me). No usb c - usb c cable is not instructive.

@PhonoPhi oled shows f.audio on start up. Have you upgraded firmware? How does it sound to you?

OLED screen is nice, I will see how to .make it useful.
Second, the sound did not impress right away, but I can be biased my more transparent and spacious sound iof E44, DC03 pro and Tanchjim space recently.

Then, with KS01, I also got Lusya ES9018 (quite big aluminum one), and I liked 9018 sound more at the first impression.
KS01 does not sound bad by any means, it may have a good potential. I will try to readjust, especially after getting AP90 - the last in my shopping spree and an interesting (to me) AK implementation.

I rarely upgrade firmware.
My recent experience with Shio upgrade was traumatic.

Received this today, unfortunately it does nothing when I connect it to my phone. Only works on my pc

Probably I'm going to buy it. I need for sure the link for the firmware update! Can you provide the link?

@PhonoPhi ks01 is buggy with firmware i received originally, strongly suggest for you to try updating it and let me know if you need any help.

@duracell071 which phone? have you upgraded firmware?

@Kindlefirehditaly i've re-uploaded firmware and drivers that i received from ali seller for you and other users who may need it. the link is active for 7 days. https://we.tl/t-kPhrqw7062

Can you describe how you upgraded? The instructions are in Chinese! Thank you! And i see 2 firmware! One got indipendent volume and the other one volume depends on the device is connected! Are you using the V22?