Should I buy a seperate dac?

Generally speaking, an outboard DAC will improve your sound.   That's always been the case with me, at least.  Of course, there are exceptions.  That's why I said generally. 

Listen for yourself, is my honest suggestion. No reason to spend money on an alleged value that your ears don’t enjoy.

You may find a DAC that for you is just super delicious sounding. That’s when you buy.

In today's day and age though a streamer/DAC combo may be a better value for you, giving you an excellent DAC plus the ability to listen to music from Qobuz or Tidal and hopefully an excellent user experience.

Not sure if you can still find them, but the Parasound ZDac was an absolutely great sounding DAC for peanuts.   If you are dac-curious, a unit like that would not set you back too far.

@erik_squires & @wentz: looks like ebay has lots of them.  Mine has been going strong since they were first introduced.   Agree, great little DAC. 

Last year, I purchased a DAC (Chord Qutest), and it has been the biggest upgrade to SQ in my system. I often listen to streamed music, and this is where I noticed a big improvement. I did not see much improvement in CDs, though. My CD player is a Wadia 302, and I tried running it to the Qutest but didn't hear an improvement.

Nevertheless, you will not regret getting a good DAC. I haven't heard the bifrost, but I would recommend the modi 3+ or modius over the bifrost. For one, the bifrost didn't get a positive recommendation from ASR (https://www.audiosciencereview.com). I have a modi 3+ in my second system and it's a fantastic DAC for the price.