A hearing system comprising a hearing device the hearing device comprising • an input transducer for converting an input sound from the environment of the hearing device to an electric input signal (s(n)), and • an output transducer for converting an electric output signal (u(n)) to an output sound, and the input transducer - in a first mode of operation - being operationally coupled to the output transducer via a forward path, the hearing device further comprising • a configurable output combination unit (Co) in said forward path, said output combination unit having first and second signal inputs and a signal output, the first signal input being a signal (y(n)) of the forward path and the second signal input being an output probe signal (pseq(n)), and the output signal (u(n)) being electrically connected to said output transducer and configurable to consist of either of the first (y(n)) or second (pseq(n)) signal inputs, or a mixture of the first and second signal inputs, the hearing system further comprising • a configurable probe signal generator for generating said output probe signal (pseq(n)), • an adaptive feedback estimation unit for generating an estimate (vh(n)) of an unintended feedback path comprising an external feedback path from said output transducer to said input transducer, said feedback estimation unit comprising a feedback estimation filter (Algorithm) using an adaptive feedback estimation algorithm, the adaptive feedback estimation unit being operationally coupled to the forward path, and • a control unit (CONT) for generating a control signal (pct) for controlling said configurable probe signal generator based on one or more control input signals (cis1, cis2, cis3), • a detection unit operationally coupled to the forward path and providing one or more of said control input signals, CHARACTERIZED IN THAT the control unit is configured to choose an appropriate probe signal based on properties of one or more current signals of the forward path, and wherein said configurable probe signal generator is adapted to generate or select said output probe signal (pseq(n)) from a multitude of different probe signals, wherein said multitude of different probe signals comprises a perfect or almost perfect sequence and/or an almost perfect sweep sequence, and wherein said detection unit comprises a noise estimation unit providing a noise estimation signal indicative of an estimate of a current noise level or a signal to noise ratio of a signal of the forward path originating from said electric input signal, and wherein the control unit (CONT) is configured to select said perfect or almost perfect sequence or a perfect or almost perfect sweep as said output probe signal (pseq(n)) when said estimate of a current noise level or said signal to noise ratio is below a threshold noise level or above a threshold signal to noise ratio, respectively, wherein the almost perfect sequence (aPS) or the almost perfect sweep sequence is a sequence of length N and having an autocorrelation function r xx (k) aPS whose elements r xx (k) aPS for k= 0, 1,..., N-1, fulfill the criterion |r xx aPS |/|Σ k≠0 r xx (k) aPS | ≥ 10. • an input transducer for converting an input sound from the environment of the hearing device to an electric input signal (s(n)), and • an output transducer for converting an electric output signal (u(n)) to an output sound, and • a configurable output combination unit (Co) in said forward path, said output combination unit having first and second signal inputs and a signal output, the first signal input being a signal (y(n)) of the forward path and the second signal input being an output probe signal (pseq(n)), and the output signal (u(n)) being electrically connected to said output transducer and configurable to consist of either of the first (y(n)) or second (pseq(n)) signal inputs, or a mixture of the first and second signal inputs, • a configurable probe signal generator for generating said output probe signal (pseq(n)), • an adaptive feedback estimation unit for generating an estimate (vh(n)) of an unintended feedback path comprising an external feedback path from said output transducer to said input transducer, said feedback estimation unit comprising a feedback estimation filter (Algorithm) using an adaptive feedback estimation algorithm, the adaptive feedback estimation unit being operationally coupled to the forward path, and • a control unit (CONT) for generating a control signal (pct) for controlling said configurable probe signal generator based on one or more control input signals (cis1, cis2, cis3), • a detection unit operationally coupled to the forward path and providing one or more of said control input signals,