A couple of reasons actually.
1. with smaller amps and presumably smaller cabinets, trying to add low frequency extension ears up a lot of power without much real world benefit. This can also jeopardize the reliability of many smaller cabinets when they are driven beyond their capabilities.
2. The original prototypes did not have either a deep or bright switch. While further fleshing out the concept, our friend the late Chef, suggested (strongly) how much he liked the bright switch (he was also a GK fan) and in thinking it through with Al Kraft, it made more and more sense and therefore was included.
This is the last amp project that Chef worked on with us. The owner’s manual also contains his contributions.
As many of you will also notice, some of the comments and suggestions made by forum members over the past year on this topic have in fact been incorporated into this amp (lower powered, smaller than the D-800, fanless, feature set). You may not realize how important the thoughts and contributions of the real world bass playing community are when developing new products, so thank you for this.