The Metal Core Deluxe MKII models three high-gain amplifiers in one small enclosure: Duo Rect (modelled on the Mesa Boogie Dual Rectifier), Fireman (modelled on the Friedman BE-100) and VH4 (modelled on the Diezel VH4). A 3-way toggle switch selects between them, and parameter settings are saved automatically for each of the three models. Modelling uses TSAC-HD technology.

For ampless use, each amp model has a matching cabinet impulse response. Users can load their own third-party IRs in WAV format through the MetalCore editing software, which converts the file automatically. The pedal supports 512-sample IR resolution and has 5 user slots for third-party IRs. The IR can be engaged or disengaged at start-up by holding the footswitch while connecting power; the LED flashes green three times when engaged and red three times when disengaged.

A USB-C port handles firmware updates in DFU mode and connection to the MetalCore editor for Windows or macOS. Parameters can also be edited on a phone with the EFX Mobile app over an OTG connection (a Lightning-to-USB adaptor is needed on iOS). The pedal runs on a 9V DC supply and uses true bypass.