Only correct answer: "It depends"
Many fallacies on resolution between digital and analog volume, pot, vs. stepped resister vs. optical vs. transformer. Too much "religion" on all sides. Listen for yourself. My personal belief is implementation matters more. From an engineering standpoint, the answer is driven primarily by the resolution of the source.
Well, can't resist. Logic may say dropping bits is less resolution, but did those bits contain data? Redbook, 16 bits, but a remastered tape with less than 80 dB DR, you drop one bit. Did you lose anything? Fancy 24 bit stream. Is it really 24 bits of resolution anyway? Analog volume. Did you lose anything or is it below the noise floor? Digital can be more accurate but does that matter? Pots add noise, but is it audible? Do you hold to a believe from poor or obsolete equipment where it did make a difference? Any method, reducing the level is reducing the audible dynamic range. It depends.
Some DAC combo line drivers are not the best. But, are they any different from a DAC only line driver? Some are, some are not. A lot of combo units it is the same, just one mode fixes the volume by whatever internal method it uses. It depends.
Do you want to add any distortion? Tone controls, balance, maybe sub sonic or sub filtering? Differing harmonic distortion from tubes or other methods? There is a reason tube buffers have a following, just as some want the most perfect squeaky clean. Your choice, so it depends.
Do you need additional input selection? Conversion between balanced and single ended? Remote controls? Maybe a built in headphone amp? It depends.
Budget ( like my DX3pro+ all in one spec chasing wonder) to excellent ( Ares maybe, HOLO?) to stratospheric, ( take your pick) you get fewer features which pushes you to DAC, preamp, headphones amp and you expect them to pay the careful implementation of their chosen technology. After all, they want to sell you another billet case and external power supply so why add $20 worth of parts when they can sell you an $5000 box? 😁 But then you are adding in all those magic cables that destroy the world. Can't win for losing.
Some advocate passive volume controls of various technologies. Less is more. SINAD perfect. But, it depends. Does the source have the current to drive a low impedance load? How does the following unit handle a variable impedance feed? Super long cables that need low Z output and high current to drive the cable reactance? I tried one, and with my stuff at the time, I was not impressed.
So it depends. What are your needs? Can you hear a difference, or are you looking for some undefined magic that can't be measured based on a You-Tube made up way to sell adds or products? Your choice. You can always try a Freya+ and get tube, passive and ss buffer all in one. Decent I believe, but not prestige level. On my desktop, I need more than unity gain because I reduce the player output by 3dB ( yes digitally) to prevent filter clipping in my DAC. HUGE difference for the good. With my giant 2W amp and a all-in-one DAC/pre with only gain of 1, I did not have sufficient listening level for some sources so I have an active preamp with a gain of 4. My main stereo with a higher gain amp, I never get close to a 0dB output, only negative so I don't need another gain stage. I see some "prestige" preamps that are actually analog in, A2D, digital volume, then another DAC. Go figure.
It depends. IF I change DACs and IF it does not have remote volume, then I would be looking at Denafrips, Musician, and Schiit preamps. Decent, not esoteric. I can only afford to pay for sonic improvements. Not magic.