Ответ Two notes
Thank you for getting in touch. In terms of signal quality, you should notice no difference between both devices. However, if you are looking to attenuate your amplifier output, this feature is not available on C.A.B. M/M+ and is reserved for our loadboxes only. In addition, if you want to run your amplifier silently (i.e. without a cabinet connected) you must use a loadbox like Captor or the Captor X.
Please let me know if this helps and if there is anything else you need, please let me know.