Between the 92, DB4, and DB2, you can’t go wrong.
I was debating this exact thing for weeks until roughly a week ago.
Long story short, I’ve only ever owned Pioneer mixers, but have wanted an A&H mixer for years, especially after playing on them. My options were either the Xone 92, Xone 92R, Xone DB2, or Xone DB4. I spent days and days digging through various DJ forums, reading reviews, looking at pictures, and doing research. I went down to my local DJ store to play with all of the mixers and to try and gauge a better understanding of what would really suit my needs without price being a factor. Eventually I opted for a Xone 92R.
Ultimately it came down to the feel, functionality, and features of the 92 versus the DB range. I would say that if you are using turntables - go with the 92. If you’re using CDJs (with or without HID mode) and/or heavily dependent on MIDI and/or using controllers to control parameters in Traktor / Ableton, I would go with the DB4.
The DB range are solid products - they sound great and have amazing sounding studio quality effects. The FX section alone is a monster of its own and truly powerful. As happydan pointed out above though, the DB4 is overkill for many people.
The DB range also has very flexible MIDI integration which is pretty much non-existent on the 92. The DB range would definitely allow for more flexibility when using digital devices, and as a result of this, is more future-proofed than the 92. Without trying to spark a debate about analog versus digital, the 92 and both DBs sound amazing, you cannot fault A&H for audio quality. I have tested them at high levels on big sound systems and they definitely sound different, but all are fantastic. That being said, the 92 is a fully analog mixer which has a completely different “feel” to it than the DB range - it’s hard to put into words - you need to feel for yourself. Everything on the 92 is rock solid - it feels like it could withstand a hurricane. All the knobs and switches on the mixer are high quality and silent. On the DB range, I noticed that while the buttons were aesthetically pleasing, they were very loud in comparison and also felt more delicate and more easily prone to scratches than on the 92 due to the metal finish that they’ve used on the DB range.
The DB range are miles ahead of most, if not all, the DJ mixers that we’ve seen released in the last few years. However, the 92 still seems to hold the throne in terms of build quality, functionality, and integration. Between the 92 and DB4, the 92 is heavier, feels more solid, and feels like it would be able to take more abuse.
In terms of why many DJs still swear by the 92, that’s probably because it has been on the market for so long and has become a permanent staple in many bedrooms and clubs around the world. DJs are familiar with it and like working with it because of it’s impressive track record, functionality, and high quality output. In the end, the 92 may be one of A&H’s older models but it is their flagship product and one of the best mixers available today, even after all these years.
To answer your question on the sound card - realistically, how many channels do you think you’ll be using? I think the Audio 10 allows for endless possibilities and I bought one despite only using two channels now, just in case I want to add anything in the future.