You may not need a new recorder--just a battery module to deal with the hot signal.
If you are trying to record mics directly into Mic-in, that could be your problem. At metal volumes, the mics themselves can overload--and I expect that most internal mics would as well. Then mic-in goes through an internal pre-amp that amplifies the signal more, another chance to overload.
An attenuator cuts down the signal after it comes out of the mic, which makes things easier for the Mic-in preamp. But if the mic has already overloaded for lack of power, it can't fix that.
I record most amplified music, including metal, with mics (CA-11) into a 12-volt BATTERY MODULE into Line-In. Extra power from the module to the mics lets them handle louder sounds. And there's no preamp behind Line-in., but the battery module supplies enough power to get a nice clear signal recorded.
Read the Soundpros page for the CMC-4 and it talks about power options.
https://www.soundprofessionals.com/cgi-bin/gold/item/SP-CMC-4U The SoundPros SP-SPSB-10 is probably fine, or use their online chat to doublecheck what would work best with your mics and recorder.