Connecting passive bass to KB amp, mixer

[.Mike]

I recently purchased a bass. As a guitarist, I have no bass amps. The closest I have is a Roland KC-300 keyboard amp that I garbage picked and fixed a number of years ago. Since it is full range, it should be perfect for low-volume bass amplification.

I've been plugging in to a line in. Best I can gather, it has a 20k - 30k input impedance. Obviously, this is much lower than a bass amp would be, and not ideal. There is a balanced mic input, but I assume the input impedance is even lower than the line in.

I tried slapping a buffered pedal in line, and it definitely improves the sound-- crisper attack, and less mushiness.

Is a simple opamp buffer all I need to raise the impedance that the bass sees, and lower the impedance that the amp sees?


Along the same lines, I want to connect the bass directly to my Yamaha mixer, which has an input impedance of 10k on line ins, and 3k on mic ins. I've read a lot about the Jensen DI transformers, but I just can't imagine spending $75 on a passive component when something active would probably cost just a few dollars and do just as good of a job. So my second question:

Do I really need a DI to connect this to my mixer, or, like the amp, can I just use a buffer to get me most of the way there?

Thanks in advance!

Mike

[petemoore]

I tried slapping a buffered pedal in line, and it definitely improves the sound-- crisper attack, and less mushiness.
  Buffer drives current, although the voltage gain is 1:1, the current gain is getting the HF's and all the HF's [and all else] to the input in a more 'intact' form.
   Is a simple opamp buffer all I need to raise the impedance that the bass sees, and lower the impedance that the amp sees?
  If the buffered pedal in bypass 'does it', 'it' is lowered output impedance + drives X input impedance more effectively.
  So the case is low input impedance is pretty easy affair to arrange electronically, a transistor or opamp, a few parts...