Didn't realize that this is the last one Won't be making anymore for quite awhile. .................................Shipping Included...............This buffer works well with the iFi power supply. The iFi uses cross cancellation signals in the power supply that cancel out the noise. Pretty impressive thinking there. And the iFi power supply comes with any adapter that you might need for foreign power, or a different tip to be used on the DC end. Note: This is a 15 volt supply that works well with this buffer, but not intended for say 12 volt units, so don't make that mistake. Use only with this buffer amp and you will be fine. .................................. These units do not have a volume control. What I have done here is to put in what I would call a gain control. I say this because a buffer amp does not increase the volume, but is a 1 to 1 ratio or so in volume. I have found that putting this control in the circuit helps me keep from overloading these tubes (rare). You don't cut it back very much, so don't fret about too little gain. This product may be one the coolest that I have ever made to date, but it is Pete Millet that brought the design to us. Thanks so much Pete for your design! So it is based on a 'new' tube device made by Korg. Just call them tiny tubes. I couldn't take my eyes off them and wanted to get on it ASAP. I did, and I will just say, it is the power supply that makes this thing sound like it does. So, these buffer units that I have been making vary by design, sound and experience (your experience, that is). If there is a more 'tubey' sound to be had, this is it. You like it you keep it. If it doesn't 'work' for you send it back in perfect condition and receive a full refund. Simple as that. Ask my customers. So far, I have not had a single buffer unit returned. 'Nuff said. To be clear, this sale is for one unit. I also made one more of these units, as you can see in the photos. It operates off of two 9 volt batteries. Inquire if interested. I won't be making anymore of these 'cuz in the near future, just look for a new product from this design in the form a headphone amp.