I am very pleased with my andromeda. It may not sound as analog as some of the 70's synths but a6 still can do some of those sounds very well if you know how to program it. I don't really need those "old sounds" very much. I produce mainly trance music, ambient, psy/goa, techno etc..
I find a6 very useful for that.
The analog oscillators and filters give the sound more punch and livelines while the digital technology controls everything.
This is a very complex synth. For example the Envelopes don't just have simple ADSR, but Attack, Decay1, Decay2, Sustain, Release1 and Release2. And it doesn't stop there.. You can choose between logarithmic, linear or exponential curve shapes. You can also modulate and loop the envelopes, set delay and so on... A little confusing in the beginning because you may not get a sound you want if some of the special parameters are not in the default-position.
The 2 filters can be configured in many ways and you can set the output levels for lowpass, high pass and bandbass at the same time for the filters to get many different kind of sweeps.
And then there are the LFOs... You can choose the waveform, speed, delay, phase, offset, level, pulsewidth (with triangle you can sweep between saw and triangle) and polarity. You can even make the lfo-waves clip. It's like working with a damn oscilloscope and a signal generator!
I have found that you have to be more careful when setting the parameters with andromeda to achieve good results. It's complex and analog but I can live with it. In fact I love it! I sold all my other keyboards away. I still have my andro and some analog modules.
Here's a picture of my queen:
link to the picture
Here's also a link to a directory which contains some of my synth demos. Many andromeda clips too...
link to the demo mp3 clips
All the clips "andromeda..., andro or a6" have been (at least partially, usually fully made with andro) made with an alesis andromeda.