Depends what you mean by safe. But it wouldn't be useful; it's a higher impedance output (1.5K volume pot at the output).
You could use the original Zen or the SOZ. Or you could try some of the excellent designs at: http://www.headwize.com/
funny you ask that-I use the BOZ as my preamp and I have three outputs on it
1-record output from the input selector
2-normal output from volume control to amp
3-pre volume control output
My headphone amp has two switchable inputs,input one is from the rec out,input two is from the pre volume control output.I use this due to my headphone amp having its own volume control,and use the BOZ gain only on sources with not enough gain to drive the amp using the rec out
Good idea, switch out the gain stage if you don't need it. Have you tried using your outputs 1 and 2 with the volume set to produce a gain of 1 so as to A/B test the BOZ? I always wondered if the great sound of the Zen series was because they added some distortion. Does it by any chance sound better with the BOZ in circuit?
Both the BOZ and Szekeres amp use the IRF510 mosfet so have similiar sound,but remember,the BOZ operates in the inverting mode as does the ZEN amp.That means the pair produces a non-inverting signal when used together but when used with a non inverting following stage you will end up with an invrerted signal.The szekeres follower is NON inverting so the result is an invertied signal.
The sound-different in combination but not necessarily wrong.Who knows what the phase is of the recording (how many inverting stages used in the signal chain ?).On some material the difference is like going from an active preamp to a passive line stage , more dynamic and punchy.Is it distortion ? No clue,but sounds good to my ears and that is the bottom line.Some do not like the "MOSFET" sound.When used in Class-A it suits my musical taste like nothing else does.Just my opinion
That is a tough call,I can change the sound of the BOZ according to what brand of coupling capacitor i use.The gain stage itself sounds very clean while not having that "etched" sound which to me causes listening fatigue with long listening sessions.
In a purely philosophical vein:
I'm always curious when I hear comments such as 'pleasing artifacts' or one classic that was phrased contemptuously to me,"it sounds better than music"...why is it that people react with suspicion--and sometimes with hostility--when things sound good? Is there some deep-seated need in audiophiles to 'suffer for their art' by listening to equipment that sounds somehow less pleasing?
just a thought but you could just hang a couple of BUF-634 or BUF04 off the output and add maybe an audio express jung regulator board for a small internal headphone amp that would take up little space in the BOZ.The Szekeres is definately a two box solution when you consider the heat sinking and power supply requirements
I agree, if they are "pleasing" artifacts, isn't that what we want? I am reminded of 2 things: an editorial somewhere once that said, "that warm sound of tubes is actually distortion"; and the "Tubehead" preamp that allowed a mix of op-amp and deliberately distorted tube stages. You could adjust the mix, which I bet would be different for different music.
That's why I asked about the difference in switching in the BOZ stage.
I believe they are the ones published in Audio Amateur (#3, 1995). If so, you can buy circuit boards: http://www.audioxpress.com/bksprods/pcbs/circuitsbuild.htm
I remember there have been updates to the original article; some builders had oscillation problems. Best to get an updated version of the schematics.