Before Martin Koubek's forming of the new band, he had come through an interesting practice among Czech cultural events. In the late seventies he (being still a student) formed a thoroughgoing band called REGRESE. The play list included mainly songs of British and American interpreters such as Rolling Stones, Cream, John Lennon, Black Sabbath, Deep Purple, Led Zeppelin, Ten Years After, Santana, C.C.R., Atomic Rooster, Jethro Tull and the like. A professional career in the band PROMĚNY of the ex-Shut up singer Jiří Helekal followed. Martin Koubek has strengthened his career in a list of bands including Michael Kocáb's PRAŽSKÝ VÝBĚR (at the time a brilliant jazz rock group), Radim Hladík's BLUE EFEECT and also enjoyed rehearsing with Marián Varga of COLLEGIUM MUSICUM in Bratislava.

Later working as a studio player Martin Koubek experienced recording with all chief Czech rock and jazz-rock musicians. Martin Koubek took also a number of part-time jobs, playing guitar and bass guitar in night bars. In the early eighties Martin Koubek played for two years with Michal Prokop's FRAMUS FIVE, later he turned to swing orchestra led by Milan Chladil and Karel Hála.

For a couple of years Martin Koubek worked as a private music editor simultaneously.

The frst years of DUX's existence (from 1985 onwards) were connected with absolute dismissal of members of official culture management. Problems arose within writing lyrics, preparing public performances, and taking part in obligatory quali?cation exams. Beginning with the year 1986 Supraphon (one of the two official record publishing company at the time) kept on releasing a sole DUX's LP single every year, which every time was sold out immediately after being put into sale. Anyway, the long-playing album recorded in 1986 was released officially in 1992. At the beginning the music of DUX reminded partly the sound of Carlos Santana Band due to precise work of all the instruments used: guitar, bass guitar, Hammond B3 organ, drums and percussion.

The original line-up included a legendary and very popular bass player Vladimír Padrůněk. Live performances were very successful and the band became known even abroad. The name appeared in Finnish press and DUX records were being taken to Helsinki (that was done illegally – it was the only way to satisfy Finnish fans who desired to hear these songs on national radios). In the late eighties the work of Martin Koubek and DUX was strongly motivated by political situation. The band started to sound harder both in music and lyrics. Because of Martin Koubek's taking part in such organization as Radio Free Europe or Voice of America and his friendship with dissidents no official album could have been released before the early nineties.

The band always has insisted on its own style we can call hard-jazz-blues-rock a sound based on brilliant composing, coordination of all the instruments, and precise instrumental performance. The original line-up settled as a quartet: singing guitarist, bass guitarist, keyboard player, and drummer. In 1986 a solo singer joined the band, however, after one and a half year he was asked to leave due to his health problems caused by alcohol. After Radek Čermák (the solo singer and occasional guitarist) had left the line-up was as follows: Martin Koubek – guitar, harmonica, vocals, Vladimír Padrůněk – bass guitar, Odon Schliesl – keyboards, Josef Nováček – drums.

However, shortly after Radek Čermák's departure Vladimír Padrůněk left the band and quitted his musical career as a consequence of his health problems (he died in August 1991). For a short time his replacement was Luděk Adámek and later DUX played as a three-member band while bass line was performed by keyboards. In autumn 1989 Michal Vik joined DUX on bass guitar.

Martin Koubek wrote non-conforming rock songs with temporary lyrics and every live performance was a protest against the pressure of the totalitarian system and the stuck situation. In autumn 1989 a video recording DUX concert is made, being, however, spread unofficially. The band was invited to perform in clubs in Amsterdam. In the year of 1990 the frst official album "Máme všeho dost (We've Had Enough)" is released through Supraphon (in fact it is the second long playing album as the ?rst one was not officially released). It was the reason why Jethro Tull invited the band to play at their Prague concert (4th July 1991). DUX played its part with enthusiasm and the concert of 17 000 visitors was a real success.

In May 1992 the album "DUX - Vladimír Padrůněk in memoriam" (recorded in 1986) was released through Panton.

At this time the line-up was completely changed and Martin Koubek played with drummer Martin Procházka and an American bass player and singer, Michael Richard Franklin. This fact started the desired direction of the band - music with lyrics in English. Besides proved songs (Cream, Jimi Hendrix) the band played original music. Having worked together for two years the musicians set out for new album "The Thrill of Love" inspired mainly by introvert feeling and personal experience of Martin Koubek. Michael Franklin wrote all the lyrics and also DUX's version of Jimi Hendrix's The Spanish Castle Magic was sung by this talented musician from California. A video for the song They Took Away Your Daddy was shot and the album was released through Reflex Records – Monitor. The band played live in three musicians as the keyboard parts for the album were recorded by a studio guest Jan Polešovský. Just before the album was ready to be released Martin Koubek had successfully completed his composing educational programme at a jazz music school Konzervatoř Jaroslava Ježka.

After Michael Franklin had quitted his musical career (having spent two years in DUX) bass player Petr Dvořák joined the band.

Videos for Sad Shadow / Smutnej stín (both English and Czech version) were shot and a "CD Single"was released including two songs and one instrumental work.

In June 1996 Martin Koubek sent the album The Thrill of Love to Deep Purple management and his band was chosen to play at Purple's concert in Ostrava (4th June 1996). The concert was a great success and an unofficial video was made. Having taken part of festival and club concerts Martin Koubek quitted active performing and went in for composing and solving personal problems

In the end of 1998 three CDs "DUX - Jenom jako" are released through Bellatrix Company . The albums included even previously unreleased songs from 1985 (with bass guitarist Vladimír Padrůněk) and a live record from autumn 1989 with the band's obvious reactions to political system. Such an attitude was of course very dangerous at that time and this was the reason why the album couldn't have been released before. The albums also included two instrumental works of Martin Koubek, which were composed for the last theatre performance of a world known Czech mime Ladislav Fialka. And even the songs sung in Czech were not omitted (the ones from the time of The Thrill of Love). Martin Koubek also shot videos for the song The Thrill of Love / Rád si to s tebou rozdám, both English and Czech version.