Metrum sounds good, but make sure it's the sort of sound you want. IME, very smooth, very easy to listen to, not particularly warm or cold sounding, very good vocals, and generally just pretty engaging and musical (just not in an overly dynamic or exciting way...hard to explain). However, of all the DACs I've tested so far, they are definitely the least resolving, so you might find it TOO smooth. If you don't mind missing out on some small details and want that really smooth, very easy going sound, Metrum is a good choice.

Gungnir is also pretty good and definitely smooth to listen to. Based on memory, I think it has a bit more bite and a bit less natural sound/timbre/tone than the Metrum or some other R2R DACs, but I was very pleased with what I heard (even for my tastes). It's good Schiit.

Now, there are other R2R or similar DAC chips/modules out there that have inherently better performance than whatever the Metrum DACs use. You can find R2R NOS DACs that have a similarly smooth, liquid, and fatigue-free sound without sacrificing nearly as much detail as the Metrums. The 1704 chips fall into this category...the NOS1704 I had for a while was more intimate and syrupy than the Metrums, and those 1704 chips can apparently be a bit soft sounding, but the NOS1704 also had noticeably more detail come through than the Metrums. So you CAN get R2R NOS sound without smoothing over stuff TOO much like the Metrums can. I'm just not sure you'll ever get the sort of detail extraction from an oversampled DAC, though for some, like me, that might be exactly what you're looking for.

In regards to the above paragraph, you may want to consider one of the MHDT Labs DACs. Some of those are right around or under $1K. They tend to use PCM56 chips, which should perform better than the Metrums on paper. Though not sure if you want a tube DAC or not. Another cool thing is you can swap out the DAC chips in the MHDT DACs for either higher quality PCM56 chips OR the AD1865, I believe it was, for a different sound. At least, that's what I read on a few forum threads. I've read good things about these DACs and am considering a purchase in the future.

I also wouldn't hesitate to recommend some of the Wolfson-based DACs (some, not all). In particular, if you can find something that uses 2x or 4x oversampling, slow roll-off/soft-knee, minimum phase filters, you might really like that sort of sound. It was sort of a "best of both worlds" thing for me on those couple DACs I tried, and those implementations generally sounded more "analog" to my ears than most other oversampled, S-D DAC. For example, I liked the Audio-GD NFB-3.2, so I'm hoping their newer, pricier Wolfson DACs with selectable filters are even better. The AMB Gamma2 is also pretty damn great despite its size and cost, though the unit I tested did NOT have the ASRC in place and was limited to 16/48 max (I thought it sounded great!). But I guess in general I just prefer low or no oversampling, upsampling, etc. Just easier for me to listen to long-term that way, apparently.

Oh, one more thing. Metrum recently put out a new DAC module (called Transient something or other), and it looks to be a better performer than what was used previously, at least on paper. Something like 0.03-4% THD vs 0.008% THD on the new module. I think it has lower linearity errors too? Either way, there's a good chance it's based off their previous chips but with improvements in place, probably software trimming, but it remains to be seen if the gains on paper will translate to noticeably better sound. Metrum did announce they're working on a new DAC with those modules, so it might be worth keeping your eyes peeled.