That depends a lot on the bass. Active pickups may be fine plugged into a mixer. Passive pickups may sound better into an active DI.
Do you have a bass amp? I know both of mine have DI's built in.
What you're essentially dealing with here is an impedance mismatch. Your bass is a high-impedance device and since your mixer accepts only low-impedance signals at the line-in, there will be a tonal forfeit. Generally you'll notice a difference in the top and low ends of the signal in a case such as this. The XENYX 802 will indeed put out a balanced line level signal at the mixer outputs (which should not be plugged into a mic preamp, but a LINE IN), and in that way it becomes a pseudo-DI, but remember that a DI is a device that accepts a HIGH-IMPEDANCE signal, which it then converts to a LOW-IMPEDANCE signal to be accepted by a mic preamp. All of these aspects affect tone.
Cheers
So, I think what you're saying is although the mixer is useable as a faux-DI, it's audibly beneficial to use a DI box - this way, I can go from it directly into my Fostex recorder & bypass the mixer altogether and better/truer bass tones?
I would always use a DI, or an Instrument input (if your mixer or Preamp has one) never a line input as it effects the tone. With taking a DI direct to the Fostex, I don't know what model Fostex it is, but a DI cannot be plugged into a line input only a XLR mic input as a DI converts an instrument input to a balanced XLR with ohms to suit a mic.
Alan
Cool. I was once advised to mic both the bass and the strings, but have never been able to try it.Some of my best bass tracks are a combination of both micing the speaker and a Di input.