Quote: Cmoy definety can drive K550. O2 drives both K550 and K501 very vell. O2 is not portable too much, by the way. I am not assume, I tried them in long term all together. Cmoy, O2, K550 and K501.

Did you try another PC? another Windows version?  

Quote: Actually it was 3 AM in the morning an it must be "made in Austria", of course.

Quote: I owned three of them and I say, Power has less defination, less details, less sound stage and imaging, more forward staging, more mid centirc, more warmth... BA has middle defination, more fullness, more neutral, less sparkling than Studio, full in mid-bas section... Studio...

Quote: The BA is not capable to drive big cans inc. K550.  Even the Studio cant drive K550 correctly. As first imperession, you think its enough power comes from cans but when paired with a decent amp it will run. I suggest you to pair it via O2.

I tried hm-602, Rocoo Studio, BA and Power and I think Sflo2 is better some aspects. Especially in quartet, trio, acustic music like jazz and folk. Also good in rock and hard rock.

S/N:4321 . Made in Australia.

 After you connect the DAP to the PC via usb, FW utility says initializing  but start button wont be operational before 1-2 min. Wait for the right time for pressing the button. If you miss the button dont be panic and keep waiting. After a few round you will be able to press it. I guess it works.

If you will spent more time in GYM than others I wont advice PFE. PFE is very good iems but in gym you will sweat to much and PFE's filters will affect nad the ear tips isolation will reduce. So, dont go GYM with PFE's.  

And think about PFE 111-112-132 (all the same) for clarity, flat response and details which is probably in the badget range.

I am not a classical audiophile, not a gear collecter or not a "my gears beat your gears" man. I am listening music since 1985, till the day never give up. Simply I love music and reliable sources/mediums. I love talking about recordings and playback philosophies. I try to experiance live...

Quote: BA sound is more neutral while Studio has more defination. Studio has a problem with upper-mids and mid-bass section. It's sound a bit tinny because of less entity on mid-bass section. But Studio still has more clarity and good in bass and sub-bass section