I think I can solder !
Maybe will make some little exercices before on other more basic stuff.
The fear I can have would be more axed on the mistake I can eventually make in pieces to solder and respective appropriated places to…
Please, what is the difference between the only x0x heart and the combo of Pacemaker + x0x ?
The PCB you have is the only x0x isn’t it ?
Good evening 
Obvious difference here. Same PCB.
http://www.openmusiclabs.com/projects/x0x-heart/index.html
On the video you can see a basic result.
With PCB only you have to buy and choose resistors, understand the procedure. I can tell you what resistors I ordered. Maybe less soldering, but more complicated. If you have the money, I think PCB + Pacemaker is easier.
Obviously Pacemaker is for eurorack integration. If you have an eurorack it’s great, otherwise you can do just like sezare. The x0xheart itself is already assembled, you just have to add sockets and pots. Like I said, the Pacemaker is probably not a beginner friendly kit but I’ve seen much worse. Just take the time to read the instructions, solder with a decent iron and you should be fine.
Your turn :
first seconds could be ea1… but not after.
Machinedrum only through AH. 
A looped single saw as synth.
nice ! The machinedrum is the only elektron box I never had. I wish there was a new version.