Go to this link: Tascam DX-2D, DX-4D DBX Modifications has all the info you need to mod a DX-4D to standalone use.
You don't need to solder either, I just made a jumper out of a stiff wire lead from a part I didn't need. I'm not sure if the 2340 is 15 ips or 7.5 ips speed. Type I dbx is *recommended* for 15ips or higher, it can be used with a "well calibrated" deck at 7.5 ips, Type II is *recommended* for 7.5 ips or slower. If you stay at 7.5 ips or higher you should be fine with the DX-4D.
PM me again if you need more help but the mod is really really easy. It takes longer to unscrew the bottom panel....
You don't need to solder either, I just made a jumper out of a stiff wire lead from a part I didn't need. I'm not sure if the 2340 is 15 ips or 7.5 ips speed. Type I dbx is *recommended* for 15ips or higher, it can be used with a "well calibrated" deck at 7.5 ips, Type II is *recommended* for 7.5 ips or slower. If you stay at 7.5 ips or higher you should be fine with the DX-4D.
PM me again if you need more help but the mod is really really easy. It takes longer to unscrew the bottom panel....