Hi, Dave H.
Thanks to all of you who replied. First, I did have a small Mackie mixer in my collection, which I inserted between my microphone and the L1 Compact. It did move the feedback limit from the 3:00 position to the 11:00 position of the Channel 1 volume control, however the actual voice volume produced before feedback seemed about the same to me. Still, I learned something about preamps. Thanks for that.
Secondly, my microphone cable ends with a 1/4" plug, hence the need for the XLR ADAPTER. Would a cable ending with its own XLR connector really make a significant improvement in voice volume? I thought adapters were supposed to be neutral regarding signal strength.
Is the connection on the microphone XLR? If so then please use and XLR cable (XLR to XLR) from the microphone directly to the L1 Compact channel 1. That will probably help.
Not all adapters are neutral regarding signal strength. Without being able to see the cables, here's my best guess at what's happening.
The EV N/D 767a microphone is a low-impedance microphone with a balanced output connection (XLR). There are three pins in the XLR output.
The cable you have "My microphone is an EV N/D767a, connected through a 1/4 " plug with an XLR adapter" with the 1/4" plug may be passing only two of the three connections. If the end looks like the plug on the left, it has only two connections. The signal is no longer balanced.
To maintain the three connections (and the balanced connection), the plug must have three connections like the plug on the right. 1/4 inch (6.3 mm) Tip-Ring-Sleeve
Even if the plug is 1/4 inch (6.3 mm) Tip-Ring-Sleeve the XLR adapter may be passing only two connections, not three. That would also give you an unbalanced connection.
Depending on the cable and the adapters, you may be changing the connection from balanced to unbalanced and changing the impedance. Either or both will cause a drop in the signal of - 6 dB or more. That could be the reason you are getting poor performance from the microphone.
If the microphone is working properly and the cable is appropriate, you should not need a mixer or device between the microphone and L1 Compact channel 1.
The EV N/D 767a has an XLR output. Please use an XLR to XLR cable directly to the L1 Compact channel 1. If that doesn't help, then there may be an issue with the L1 Compact or the microphone.
Does that help?