Has Anybody built Joe Davisson's Heaphone Amp?

[Pakaloabob]

I just wired up this circuit on the breadboard:http://www.diystompboxes.com/analogalchemy/sch/headamp.html.
I think it sounds Fantastic! But I do have a couple questions for anyone who can help me.
First of all, it looks like the resistor to ground off the 2N3904 transistor reads "100/1W." I believe that means 100-ohm, 1-watt resistor, but I am not sure why only this resistor would be labeled 1-watt. I did go out and buy a 100-ohm, 1-watt resistor just to be sure.
My next question, is there any speaker simulation built in to the circuit, or is it just a straight amplifier? I tried to compare it to  Joe's "Simple Sim":http://www.diystompboxes.com/analogalchemy/sch/simplesim.html to see if perhaps the sim is incorporated in the heaphone amp, but I am not smart enough to figure it out  If not, I will probably put the sim in front of the headphone amp.
The lack of a volume control does not bother me too much, I just use the guitar's volume pot. However, at max volume (on the guitar) the signal is just at a comfortable level. I have built the schematic as shown and used a 1/4" mono to 1/8" stereo adapter to use my headphones. I am wondering if I built 2 units for stereo, as Joe suggests, would the sound be louder? Would it be worth it?
My overall plan is to incorporate a headphone amp with a cab-sim and an overdrive/fuzz/distortion to have a nice all-in-one unit to practice in silence. I am going to check out the MXR headphone amp from GGG, a couple of speaker sims from Tonepad and Runoffgroove, and perhaps a speaker saturation sim. So far I really like Joe's headphone amp and will at least combine it with his "Easy Drive" in one box. If I like any of the other circuits I might make another practice setup.
I appreciate any help or suggestions.
Thank you Joe Davisson for some great circuits!

[PRR]

Power equals voltage-squared divided by resistance.

We don't know all the internal voltages, except that none of them can be over 9V.

Assume they ARE 9V and see which ones run hot.

9 squared is 81.

Top-Left: 470K resistor. 81/470,000 = 0.000,17 Watts. The smallest resistor we commonly find is 1/4W, 0.25W. This is over 1,000 times bigger than we need, but smaller resistors are not cheaper, just harder to see. Use 1/4W here.

Top-Right: 15K resistor. This won't normally get the full 9V, but just pretend. 81/15,000 = 0.005,4 Watts. Again the 1/4W is ample.

Botton-Right: 100 ohm resistor. 81/100 = 0.81 Watts. This is not quite true (there will be some voltage drop in Q3 so the 100r has less than 9V), but it does seem to want more than 1/4W or 1/2W resistor.

A more detailed analysis suggests less than 5V across the 100 ohms. 25/100= 1/4W. However it is bad practice to run a resistor right AT its rating. I would not use less than 1/2W rating.

You can confirm this with your finger. (Only try this on low-volt stuff, 12V and under.) All the resistors run "cool", except that 100 ohm should be noticably warm.

Additionally, in DIY, mistakes happen. If Q3 gets solder-bridged there WILL be 0.81 Watts in it. A 1W part will sit there, hot, while you look for your mistake. A 1/2W part may fail, giving you two problems to find (the solder-bridge and the open resistor).

If you don't have 1W parts under your bench, use two 220 1/2W parts in parallel.

> the signal is just at a comfortable level.

Hasty changes you can try. There's other ways to skin this cat. Frankly a LM386 amp is probably an easier way to boost guitar to headphones.

Replace the 470 with a short. Change 4.7uF to 47uF. Change the output 47uF to 220uF. Now change the 100K which loops-back from Q3 emitter to Q2 base to 220K, 470K, etc.

[Pakaloabob]

Thanks, Paul!
I knew there had to be some sort of scientific reason for that 1W resistor. I appreciate you showing the formula and the demonstrating the math. That is how I am learning so much on this forum.
True, I could use a 386 amp, but I really liked the idea of this simple discrete trani amp. I actually have made a Ruby and really liked the sound, but the boost was way more than I needed for headphone use. I also have a Zinky/Smoky amp that a friend gave me. I made the terrible mistake of trying that with headphones - nearly pierced my eardrums!!! Have to be very careful with guitar volume.
I may try the resistor/cap switches you sugested, just to see how they work out. That's the beauty of the breadboard.
BTW, you didn't say if you had tried Joe's headphone amp yourself.