Just about to pull the trigger on Pontus 15th ...

@mattw73 Thank you for sharing. If your preamp has an output impedance of 50k ohms, it should not have any matching issues with the Denafrips DAC, whether using RCA (625 ohms) or XLR (1250 ohms). I was referring to my own preamp, which has only a 10k ohm output impedance and might have some issues since the ratio is less than 10. I was surprised to hear that the RCA input of the Pontus does not perform well.

@lanx0003 yeah I understood your question & concerns but I ended up babbling on about my situation. My experience with impedance matching has only been with preamps & amps as far as close calls & definite issues from mismatches. I have a 10k input & a 12k input amps. I've been as close as an 8x's difference between the 2 & didn't notice any meaningful issues. I've had preamps in that 5k range & probably higher depending on frequency where noise & brightness occurs. Stuff like my old PAS preamps caused issues with all my modern day solid state amp. 

I've run my MTK kit preamp which can be as High as 1800ohms sound quite nice with my 10k amp. Not exactly the same situation between dac & preamp though. Maybe someone else will chime in with something similar to your exact question. 

Wow, no apparent issue from 10k to 12k! Maybe I, along with many others, have been overly concerned. But here’s my experience: I used a preamp with a 5k output impedance into an amp with a 20k input impedance, and the sound felt restrained. However, this particular preamp was well received by some, if not the majority. I tend to attribute this to a matching issue.

I had been eyeing Denafrips for a long time, but its high output impedance was always a hurdle that kept me from pulling the trigger. Then the Harmony DAC had the same design—until this micro DAC came along, seemingly designed to address matching concerns. I don’t know. I guess I’ll never know until I try, right?

Yeah my 2 lowest impedance amps are an Arcam PA240 at 10k & a Rotel RB-1582mkii at 12k..this is their single ended inputs. Not an issue with solid state but I favor tube preamps. When I bought the Arcam I was unaware of its input. I had a Arcam SA30 & liked the amplification of it so much when I saw a deal on the PA240 I grabbed it. At the time it was an issue for my favorite preamps & I regretted buying it. It was very disheartening. 

With preamps you can compensate a little by upping the value on the output caps which most tube preamps have. But when the match is really bad it's like you said..less drive/gain. I'd have rolled off bass & hot treble. If the match was really bad it will add noise into the system. Also a lot of times what the manufacturer specs isn't always legit. It could be a 1k output at 1khz with the volume full blast..with the impedance actually being much higher at other frequency's & volume levels. 

My kit amp that is 1600ohms at its highest & that I said paired well with the 10k Arcam was actually rated at 800ohms by the designer..which he measured at 1 frequency. 

In your situation without knowing for sure how the Pontus would match I would probably try something like the micro first. Then if maybe you don't care for the micro you could go for the 15th. Personally I'd like to hear your thoughts & opinions on the Harmony model. I'm going to give the Pontus a lot more time but I'm not really impressed with it thus far. I've been strictly using my Icon preamp & Fritz REV7 SE speakers but switching amps every couple days. I work from home & listen to music 6 or 7 hours a day..with at least an hour of it sitting between the speakers. I listen to a lot of music. When I'm not playing music I have the TV going thru the dac. It still hasn't even been a week though so I'll pump the breaks on criticizing it more than I already have. 

I think that Harmony uDac looks pretty cool. I like that one has the choice to use their own power supply. The guys at Vinshine think it's a great value piece..which is usually the stuff I'm always interested in. It's getting good reviews but then all these R2R's seem to get that..but this unit is under $1k before tax. No impedance issues either. 

@mattw73  According to Wave Theory, the new Denafrips 15th leans toward the bright side of neutral, in contrast to the warmer sound signature of the original Pontus or Pontus II. The treble resolution is enhanced, but it lacks the rich mids and powerful low-end slam of the Schiit BF II.  When streaming high-resolution OS files, its sound quality might be on par with the Laiv DAC. However, when the Laiv DAC streams high-resolution OS files, the gap becomes more apparent.  In short, system pairing—including the amplifier and/or preamp—is critical. If your system is already bright, the Denafrips 15th might not be the best fit.