An assembly, more particularly a turbomachine, includes a shaft, which extends along an axis, a shaft seal device for sealing an annular gap between the shaft and a stator in order to seal a process fluid chamber in relation to the environment. The shaft seal device has a ferrofluid shaft seal. At the process fluid chamber, the shaft seal device includes, in addition to the ferrofluid shaft seal, an additional shaft seal. The ferrofluid shaft seal is arranged at the annular gap axially between the first shaft seal and the environment. A pressure sink is provided at the annular gap axially between the additional shaft seal and the ferrofluid shaft seal.