Long story short, I got bored and built a SP-14 to go with my Latino ST-120. I am running my amp through a home theater amp for convenience in volume control and switching.
St -120 build thread here
After reading some reviews about how nice the SP-14 sounded I thought I would give it a try.
I didn't want to lose the convenience of remote control volume and source switching. There are a few options out there that allow you to to add these features to the preamp but most were not quite what I wanted or the quality was poor. I decided on an AMB LCDuino-1 setup with volume and source switching. It has many great features and has full user customization, but that project is a whole nother thread.
After a few months of work the preamp is up and running. I ran through some initial tests and fired it up. Everything worked first try flawlessly. (I didn't think that was suppose to happen with DIY)
How is the SP-14 sound?
There is none. in a good way. I hit mute and its dead quiet. My system has always had a little bit of fuzz when you put your ear to the tweeter but this amp has almost made it gone. I hit play and the system comes alive like never before.
The biggest two changes I have noticed is the background and the soundstage. Its hard to explain but the musical notes spring up front and center (or sides depending on recording) and gently decay into a dark space I never new existed. Vocals are smooth enough to make the hair on my arms stand up. If you are in question of buy this amp just do it. You wont be disappointed.
About the build.
Started The chassis the same as my ST-120. Wood front and sides, aluminum top, bottom, and rear. I made the rear out of 1/4" aluminum so I can drill and tap the edges 4-40 to screw the top and bottom plate to it. Its too thick for the rca connectors so I had to machine the inside rear out to about 1/16" thick. That was the hardest part of the whole build since I don't have a machine shop in my basement.
Heres a pic of getting some holes done
Inside pic of rcas in the completed amp. You can see the AMB input output selector wiring. I used different wire on different outputs just to try. I had some solid silver sitting here left from another project
Finished rear looks like this
Here is the internal wiring of the LCDuino. Left to right we have a small transfomer (always on) 5v power supply, Power mom switch, Motorized pot (used as an encoder, there is no signal going through it), ir receiver, and the LCDuino board with lcd display. Bottom pic far right is the control board for the AMB relay based stereo and selector boards.
Wiring the SSR and power distribution for the transformers.
A couple more pics of the inside of the amp.