I'm on the fence for a DAC. Sound quality wise should i buy the Holo spring 3 dac or the Musician Aquarius, which have about the same price range.
My set up is Cambridge CXN v2 and CXC CD transport, Rotel A12 integrated Amp but looking to upgrade this last one, and KEF LS 50 Meta.
The correct answer is neither. Your problem is you have been reading and hanging out with totally idiotic audiophools lacking a lick of rational thought.
You already have Dacs, one in your your streamer and one in your integrated amp. You will not hear a wit of difference between any of them, and any other proposed DAC no matter how much it costs. Any minute measured difference will be dwarfed by other issues.
The sound of a system is dominated largely by the speakers and their interaction with the room
Now a room's contribution is very much dependent on the speakers in room total response. That is to say if the on axis response does not mirror the axis response closely, then there will be a mismatch between the direct and reflected sound which is a serious issue and not correctable by equalization.
Now, I have heard your speakers, and they are above average in many respects. However the midband dip at 2K and the rise at 4K is audible, making the speakers retiring and a little "brittle" at the same time. However the last two octaves of the audible frequency range drop off like a cliff below 75 Hz. Between 40 and Hz there is a lot of important musical information. The 20 to 40 Hz range is can also be notable for its absence on a lot of musical material. So this issue alone needs far more attention than worrying what DAC you are using.
Next those speakers have low acoustic efficiency being 85 db 1 watt one meter. So your little integrated amp, will not drive them to concert levels in even a small room, without contributing more distortion by far than any DAC.
These are KEF's measurements on your speakers.
Below are the on axis and off axis measurements out to 90 degrees.
For a speaker they are actually pretty good, but significantly short of what is possible currently.
When considering streaming audio, attention has to be paid to your router, and your home Ethernet infrastructure. Any bottlenecks will result in throttling of your stream and lowering of the bit rate to avoid dropouts.
Generally the best way to proceed, is to have the DAC in the preamp, and avoid needless daisy chains. Streamers really should be selected on ease of use.
I do most of my streaming from a DIY HTPC made from the finest components, and I also have a DIY Digital Audio workstation, with an RME DAC devoted to that. It is a pro mixer DAC. Generally this is a much handier approach to grabbing what is out there. So the preamp DAC does the lion's share. All Digital sources go to the preamp/processor, via a digital connection.
The bottom line is that money spent on either of those DACs is money flushed down the drain as you have far bigger fish to fry, to have any tangible chance of improving your situation.
The first two items, are capturing the last two octaves of the audio spectrum. To do this requires at least one good sub, and a preamp, or integrated amp with bass management. In addition to reproducing the last two octaves, it will significantly reduce cone excursion in your speakers and improve the quality of your speakers in the range they are able to reproduce. This will increase listening pleasure and realism enormously and make a real audible improvement. Buying one of those DACs, will buy "Sweet Fanny Adams.". It may help someone with their boat payment.
