What is massive spl 61?

As an AI language model, I don't have recent information about specific products or models. However, here are some general information about SPL and SPL 61:

SPL, also known as Sound Performance Lab, is a German manufacturer of professional audio equipment. They are known for their high-quality analog and digital signal processors, microphone preamps, and mastering-grade audio interfaces.

SPL 61 is most likely a model number for one of their products, but unfortunately, without more context, it's impossible to say which product it refers to. However, in general, SPL gear is highly regarded in the professional audio community for its exceptional sound quality, reliability, and innovative features.

Some of SPL's most popular products include the Mastering Series (such as the Vitalizer MK2-T and Iron), the Channel One and Frontliner microphone preamps, and the Phonitor headphone amplifier. They also offer a range of analog and digital processors for mastering, mixing, and recording, as well as custom rack systems and accessories.