don allen gen II pre amp vs. Maple tree 4se

When I was shopping for a pre amp I considered each of these mentioned thus far and ended up with the Mapletree. I never heard the others to compare. But I am thrilled to own the Mapletree. Simple circuit, point-to-point wiring, takes less expensive 12SN7 tubes instead of pricey 6SN7 (although can do either), custom gain for each input, separate power supply, wonderful personal customer support, separate channel gains ... all for under $1k new! Since I've not heard the others I cannot compare the sound, but can say that mine sounds wonderful and has worked well as a pre to ss as well as tube amps. Rolling tubes changes the sound to your liking. If the others are as susceptible to tube rolling as the Mapletree then I'd suspect any of these would sound great. Just pick one based on their features, support, and price.

Custom gain for each input? Can you explain how that works? That type of feature has always appealed to me.

After speaking with Dr. Peppard and letting him know the output specs of my input devices he suggested 10db for my CDP and DVD player, and 18db for my cassette player, IIRC. This way, the master volume knob hovers near the middle of its travel for each piece of input gear at the volume I generally listen. Theoretically, the most linear position of the (any mechanical) volume knob is its center area. I am very glad of this feature as I often read complaints from folks with "standard" pre gains (approx. 26db-32db) that they are not able to adjust the volume to their liking because as soon as they turn it even a little the sound is already too loud.

So is the gain for each input factory set (sounds like it) or can the user set it?

IIRC, on the Mapletree, it's just a matter of swapping resistors on the source selector switch.