What works for HiFi does'nt necessarily work for the musician. Within the HiFi, technics try to reproduce the original sound as much as possible however the technics for musicians works on a base of creating, bending and designing.
In conclusion: Even the best high-end manufacture always ends up doing the complete opposite to the requirements of the musicians. We know manufacturers who developed very nice studio monitors and PA devices but are'nt able to build decent guitar amps.
In fact back in the 50's we had no decent and affordable semiconductors so a bunch manufacturers started to build guitar amps with tube technics. But even the speakers from that time period weren't the best in comparison to today's standards. Today we would say that these speakers were middle tone speakers. The tube was an industry standard and a simple technology: a couple of electronic parts around the tube, power supply, output transformer connected and you had a amp. A side effect of these devices was that it created unique distortions and sound colors, which came from the technical setup of the tube.
Based on the current vintage hype (more about this later) most people thought that this effect was created on purpose. But it is thought that it was a random effect mixed with a compromise for cost effectiveness.
The answer isn't so easy. At the perception point in the human hearing system there are the sound-formants (harmonies etc. - all described as sound color) as important as the basic tone itself. It is a known fact that a tube produces the second harmonic and it is this that will be felt as nice and warm instead of the third harmonic which will be created from the semiconductors. Even the nonlinear plays an important roll:
At the end of the 70's and during the 80's many manufacturers switched their production to semiconductors. It was obvious that this decision came from non-musicians. A business man wants to sell as many products as possible. And the easiest way to reach that aim is through lower prices. An amp based on semiconductor technics had some attractive advantages: its cheaper in production, weighs less, is compact, is service friendly etc.! Only you can't bypass the physics. The only thing you can do is to adapt the results. Probably some would disagree now saying they can emulate the tube sound (We are not talking about digital emulations at this point).
The answer is Yes and No !
Of course you can try to simulate the tube attitude through extra circuits. But when you take a closer look on the circuit layout of a tube amp you will see that the signal path is very short. This means that switching is very fast. Effectively the tone arrives immediate at the speaker. If you increase the circuits the signal needs to proceed over many stations and is much slower. Even worse, the signal loses its source and dynamic. Every element, regardless of it being a tube, transistor or IC influences the formants. If you form the signal with a tube from the very beginning and then use the semiconductor just for straight amplification, you get something interesting (apart from if you switch into "British mode" which sounds good only if everything is on full volume).
Most manufacturers started to realize this and built hybrid amps. It was advertised that a tube is included in the pre amp but through so many circuits you saw how little these developers understood about tube technics. It isn't enough to switch a tube somewhere in the signal way. The tube has to be placed in this way: pickup, guitar cable, tube and not somewhere between the first and third IC (imagine that in one IC there are more than 100 transistors)! Basically it isn't the right way and it is now too late anyway. No wonder those amps established themselves as absolute entry models only. It seems somehow sad as it could have be done better ...
Countless speculations about which component delivers the best sound also irritates us a bit. One often read and hear about carbon resistors that sound more open and easier than the metal-oxide resistors. We think it's unfair with regards to the customer. Without publishing the basic knowledge this sounds like "Diesel engines are better then benzine engines!" If you restore an old amp with the aim to rebuild the old construction and sound then it's right to use the original components. At the end it all comes down to personal taste. So the question sounds better or not is unnecessary. We had customers with panic in their eyes asking me do i use original carbon resistors without knowing what they are saying "I read that they are the ultimate vintage components". Also this strange hype around NOS components is scary. These components lie around in a storage for 40-50 years and should still be functioning ?? Imagine you do that with a car. Do you believe you can start the motor after all these years without any problem? There are components included which have aged and never been used. NOS-Sellers are rising like mushrooms in a wood at the moment.
To stay as flexible as possible we still say the sound design control should happen completely in the pre amp. The power amp should only amplify linear and push the signal a bit. And that is our Philosophy. We admit that this idea is nothing new and this construction was for a long time not hip. In the late 60's and beginning of the 70's an English guitar manufacturer built devices with an ultra linear output transducer. This was loud as hell and very hard to distort. After a while they disappeared. In the late 80's two German manufacturers started with the same idea - with a lot of success. This encouraged us to develop a pre amp with 3 different channels.
The question does the GP-1 sound great is unnecessary, you should ask: Does it feels good? The answer is definitive: Yes.